Correct answer: Centrifugal force

Explanation:
When milk is churned, the separation of cream from the milk occurs due to the centrifugal force. This force is generated when the milk is spun rapidly in a churning device. The centrifugal force pushes the heavier particles (such as fat globules, which make up the cream) outward, toward the sides of the churn, while the lighter liquid (skim milk) stays in the center. Over time, this separation becomes more pronounced, with the cream rising to the surface. This is the same principle used in many industrial processes like centrifugation to separate different components of mixtures.

Other Options:

1. Frictional force: Friction does occur during churning (between the milk particles and the churn’s surface), but friction is not the primary reason for the separation of cream. It only affects the motion of the milk, not the separation process itself.
2. Gravitational force: Gravitational force affects all objects, including milk, but it is not responsible for separating cream from milk. Gravity pulls everything downward equally, so it does not create the effect of separating cream from milk. This would only happen over time if milk were allowed to settle in a container, but churning is a faster process driven by centrifugal force.
3. Viscous forces: Viscosity is the internal friction of a fluid that resists its flow. While viscosity does play a role in the overall motion of the milk, it doesn’t cause the cream to separate. In fact, the separation happens precisely because the milk is moving quickly and overcoming the forces that might keep the fat particles mixed in with the liquid.

Thus, centrifugal force is the primary factor that causes the cream to separate during churning.

Additional Information:

• Centrifugal force: This is a pseudo-force that appears when an object moves in a circular path. It acts outwardly from the center of rotation, and in the case of churning, it causes the denser fat particles (cream) to be pushed outward, while the lighter liquid milk remains in the center.
• Application in Industry: The principle of centrifugal force is used in industrial centrifuges to separate cream from milk in dairy processing plants. The machines rotate at high speeds, efficiently separating cream from milk in a short period of time.
• Churning and Cream Separation: Traditionally, cream separation was done by hand using a churn, but modern machines have made the process faster and more efficient. The amount of cream that separates depends on the fat content of the milk and the speed of churning.

Correct answer: Magnetic field

Explanation:
A moving electric charge produces a magnetic field. This is a fundamental principle of electromagnetism. When an electric charge moves, it generates a magnetic field around it. This phenomenon is described by Ampère’s Law and is the basis for how electric current flowing through conductors (such as wires) produces magnetic fields, which is essential to the functioning of devices like electric motors, transformers, and generators.

Other Options:

1. Sound waves: Moving electric charges do not produce sound waves. Sound waves are mechanical waves that require a medium (like air or water) to propagate and are generated by vibrations, not by moving charges.
2. Light rays: While moving charges can produce electromagnetic radiation (such as light), the primary and immediate effect of moving charges is the generation of a magnetic field, not light.
3. Heat waves: A moving electric charge does not directly produce heat waves. Heat can be generated as a byproduct in certain cases (for example, through electrical resistance), but this is not the primary outcome of a moving charge.

Correct answer for the SSC CHSL Physics MCQ: Coulomb

Explanation:
The S.I. unit of electric charge is the coulomb (C). One coulomb is defined as the amount of charge transferred by a current of one ampere flowing for one second. The relationship between charge and current is expressed as:

Q=I×t

Where:

• Q is the charge in coulombs
• I is the current in amperes
• t is the time in seconds

Other Options:

1. Ampere: The ampere (A) is the unit of electric current, not charge. It represents the flow of electric charge through a conductor.
2. e.s.u. (electrostatic unit): e.s.u. refers to an old system of units used in electrostatics, but it is not the S.I. unit of electric charge.
3. Kelvin: The kelvin (K) is the unit of temperature, not electric charge.

Correct answer for the SSC CHSL Physics MCQ: Laser

Explanation:
A laser (Light Amplification by Stimulated Emission of Radiation) is a beam of light that is highly directional, meaning it can be focused into a very narrow beam and can travel over long distances without spreading much. The key properties of laser light are coherence, monochromaticity, and directionality, which make it different from ordinary light sources.

Other Options:

1. Eraser: An eraser is a tool used for removing marks made by pencils or pens, not related to light or beams.
2. Grazer: A grazer refers to an animal that feeds on grass or plants. It is not related to light or laser technology.
3. Maser: A maser (Microwave Amplification by Stimulated Emission of Radiation) is similar to a laser, but it amplifies microwave radiation instead of light. It is not highly directional like a laser beam in the visible spectrum.

Correct answer for the SSC CHSL Physics MCQ: 45 dB

Explanation:
The permissible noise level in residential areas during night time is typically set at 45 dB according to various national standards and regulations on noise pollution. This is to ensure a peaceful environment for residents, especially for sleeping and relaxation. Noise levels above this threshold may lead to disturbances and health issues such as stress or sleep disorders.

Other Options:

1. 55 dB is generally permissible during the daytime in residential areas but is higher than the permissible level for night time.
2. 75 dB is much higher than the permissible noise level for residential areas at night. This level is typically found in noisy environments like traffic or industrial areas.
3. 80 dB is also too high for residential areas, especially during the night. Such levels of noise can cause discomfort and may lead to hearing damage over time.

Answer for the SSC CHSL Physics MCQ: Temperature of the surface

Explanation:
The amount of energy reflected by a surface depends primarily on:

1. Angle of incidence: The angle at which the wave strikes the surface affects how much energy is reflected. A smaller angle of incidence (closer to perpendicular) typically results in more energy being reflected.
2. Nature of the surface: A smooth, reflective surface (like a mirror) will reflect more energy than a rough surface, which scatters the reflected wave.
3. Wavelength of the incident wave: The reflection of energy can also depend on the wavelength, as certain surfaces are more reflective for specific wavelengths (like the reflection of light).

Temperature of the surface does not directly affect the amount of energy reflected. While temperature can influence the properties of a material over time, it is not a direct factor in determining how much energy is reflected by the surface.

Correct answer for the SSC CHSL Physics MCQ: Violet

Explanation:
When light passes through a prism, the light is dispersed into its component colors, forming a spectrum. The degree of deviation (or bending) that the light undergoes depends on its wavelength. Shorter wavelengths of light, like violet, are refracted (bent) more than longer wavelengths, like red. This is because shorter wavelengths interact more with the material of the prism, causing them to deviate more.

The order of light colors in terms of deviation (from greatest to least) is:

• Violet (most deviation)
• Blue
• Green
• Yellow
• Orange
• Red (least deviation)

Other Options:

1. White: White light is a combination of all colors in the visible spectrum. While it can be dispersed into its constituent colors by a prism, it doesn’t represent a single wavelength and hence, does not have a single deviation value.
2. Red: Red light, having the longest wavelength in the visible spectrum, is refracted the least and shows the least deviation.
3. Green: Green light falls somewhere in between violet and red, but it still does not show as much deviation as violet.

Correct answer for the SSC CHSL Physics MCQ: Soft iron

Explanation:
The best material for the core of a transformer is soft iron. Soft iron is preferred because it has high magnetic permeability, which allows it to efficiently conduct magnetic flux with minimal energy loss. Additionally, it has low coercivity, meaning it can easily change its magnetization as the magnetic field changes. This property is essential in transformers, where alternating current (AC) is used, creating a constantly changing magnetic field. Soft iron also reduces eddy current losses due to its ability to easily magnetize and demagnetize.

Other Options:

1. Stainless steel: Stainless steel is not a good material for transformer cores because it has high reluctance and poor magnetic properties compared to soft iron, which would result in inefficient performance.
2. Mild steel: While mild steel is a ferromagnetic material and can be used in certain applications, it is not as efficient as soft iron due to higher losses from eddy currents and hysteresis.
3. Hard steel: Hard steel is unsuitable for transformer cores because its high coercivity makes it harder to magnetize and demagnetize, leading to greater energy losses.

Thus, soft iron is the best material for the core of a transformer due to its excellent magnetic properties and minimal energy losses.

Correct answer for the SSC CHSL Physics MCQ: RMS values

Explanation:
In AC circuits, AC meters typically measure the root mean square (rms) values of the current or voltage. The rms value is a measure of the effective value of an alternating current (AC) or voltage, representing the equivalent constant DC value that would produce the same power dissipation in a resistive load. For a sine wave, the relationship between the peak and the rms average is: rms value = 0.707 peak value.

The rms value is calculated by taking the square root of the mean of the squares of the instantaneous values over a complete cycle.

Other Options:

1. Mean values: The mean value of an AC signal (average value) is often zero for a complete cycle because the positive and negative halves cancel out. Hence, meters do not typically measure mean values for AC circuits.
2. Peak values: Peak values represent the maximum instantaneous value of current or voltage, but meters generally measure rms values because they provide a better indication of the effective power.
3. Mean square values: The mean square is used in the calculation of rms values but is not directly measured by typical AC meters.

Correct answer for the SSC CHSL Physics MCQ: Amplitude

Explanation:
When a light wave is reflected from a mirror, there is generally no change in its frequency, wavelength, or velocity. These properties remain the same because the reflection process does not alter the inherent characteristics of the light wave. However, the amplitude of the light wave can change, depending on factors such as the reflectivity of the surface of the mirror.

• Frequency: The frequency of the light wave does not change during reflection. The frequency of light is determined by the source and remains constant in the reflection process.
• Amplitude: The amplitude of the light wave can be affected by the reflectivity of the mirror. A perfectly reflecting surface would not change the amplitude significantly, but imperfect surfaces might absorb some of the energy, reducing the amplitude of the reflected wave.
• Wavelength: The wavelength of light remains the same because the speed of light in the medium (air or vacuum) does not change significantly during reflection.
• Velocity: The velocity of light does not change during reflection if the medium is the same (for example, in air or vacuum).

Thus, the amplitude is the property that may change when light is reflected from a mirror.

Correct answer for the SSC CHSL Physics MCQ: Fusion reactions

Explanation:
Solar energy is primarily due to fusion reactions that occur in the core of the Sun. In these reactions, hydrogen atoms fuse together to form helium, releasing a tremendous amount of energy in the process. This energy is emitted as sunlight and heat, which reaches the Earth and is harnessed as solar energy.

• Fusion reactions: In the Sun’s core, hydrogen nuclei (protons) fuse to form helium under immense pressure and temperature. This process releases energy according to Einstein’s equation E=mc², where the mass lost in the fusion process is converted into energy.

Other Options:

1. Fission reactions: Fission involves the splitting of heavy atomic nuclei (like uranium or plutonium) and is used in nuclear power plants. It is not the process responsible for solar energy.
2. Combustion reactions: Combustion is a chemical reaction involving the burning of a substance, such as fossil fuels. It does not contribute to the energy of the Sun.
3. Chemical reactions: While chemical reactions release energy (like in combustion), they are not the source of solar energy. Solar energy comes from nuclear fusion, not chemical processes.

Correct answer for the Physics SSC CHSL MCQ: Increased under reverse bias

Explanation:
The depletion layer in a P-N junction refers to the region around the junction where there are no free charge carriers (electrons or holes) because they have diffused across the junction and recombined. The width of the depletion region is influenced by factors such as the level of doping and the applied voltage.

• Under reverse bias, the width of the depletion region increases. In reverse bias, the external voltage opposes the flow of current and widens the depletion layer, as it increases the potential difference across the junction and drives the minority carriers further apart.

Other Options:

1. Decreases with light doping: Light doping results in a narrower depletion region, but this is not the primary cause of the width of the depletion layer in P-N junctions.
2. Increases with heavy doping: Heavy doping results in a narrower depletion region because the increased concentration of charge carriers reduces the width of the depletion zone.
3. Is independent of applied voltage: The width of the depletion layer depends on the applied voltage, especially under reverse bias, as it increases with reverse voltage.

Correct answer for the Physics SSC CHSL MCQ: Conservation of momentum

Explanation:
The working of a rocket is based on the principle of conservation of momentum. According to this principle, the total momentum of a system remains constant if no external forces are acting on it. In a rocket, as the fuel is ejected backward at high speed, the rocket itself is pushed forward in the opposite direction. This happens because the momentum lost by the ejected fuel is gained by the rocket, thus propelling it forward.

The rocket’s engine expels gases at high velocity in the opposite direction, resulting in an equal and opposite reaction that pushes the rocket forward, in accordance with Newton’s Third Law of Motion.

Other Options:

1. Conservation of mass: While mass is conserved in the rocket system, the primary principle behind the motion is the conservation of momentum.
2. Conservation of energy: Energy is conserved, but the principle behind the rocket’s motion is more directly related to momentum rather than energy.
3. Conservation of angular momentum: This principle deals with rotational motion, but the rocket’s linear motion is primarily explained by the conservation of momentum.

Correct answer for the Physics SSC CHSL MCQ: An alloy of tin and lead

Explanation:
A fuse wire is typically made of an alloy of tin and lead. This alloy has a low melting point, which allows it to melt quickly when an excess current flows through the circuit. The purpose of a fuse is to protect electrical circuits by interrupting the flow of electricity when the current exceeds a safe limit. The tin-lead alloy is chosen because it has the appropriate properties for this function, especially its ability to melt quickly and break the circuit in case of overload.

Other Options:

1. An alloy of tin and copper: While tin and copper are used in various applications, they are not commonly used in fuse wires because they do not have the low melting point required for this purpose.
2. An alloy of tin and aluminium: This alloy is not typically used for fuse wires either, as it doesn’t provide the right melting characteristics for overcurrent protection.
3. An alloy of nickel and chromium: Nickel and chromium alloys, like nichrome, are used in heating elements, not in fuse wires. These alloys have high melting points, making them unsuitable for fuses.

Correct answer for the Physics SSC CHSL MCQ: Geo-thermal energy

Explanation:
Geo-thermal energy refers to the energy that is stored in the form of heat beneath the Earth’s surface. This energy comes from the natural heat generated by the decay of radioactive materials and from the residual heat left over from the formation of the Earth. Geo-thermal energy can be harnessed for heating, cooling, and generating electricity. It is a renewable energy source, as the heat from the Earth’s core is continuously replenished.

The Geothermal energy of the Earth’s crust originates from the original formation of the planet (20%) and from radioactive decay of minerals (80%).Current worldwide installed capacity is 10,715 megawatts (MW), with the largest capacity in the United States (3,086 MW), Philippines, and Indonesia.

Other Options:

1. Thermal energy: Thermal energy refers to the energy that comes from the heat of any source, not specifically from beneath the Earth’s surface. It is a broader term and does not focus on Earth’s internal heat.
2. Nuclear energy: Nuclear energy comes from the reactions of atomic nuclei, such as fission or fusion, and is not directly related to Earth’s internal heat.
3. Tidal energy: Tidal energy comes from the movement of ocean water due to the gravitational pull of the moon and the sun, not from beneath the Earth’s surface.

Correct answer for the Physics SSC CHSL MCQ: There is high pressure inside the boiler

The temperature of boiling water in a steam engine can be higher than the normal boiling point of water because there is high pressure inside the boiler. When the pressure is increased, the boiling point of water also increases. This is a result of the fact that water requires more energy (higher temperature) to transition from liquid to gas when there is higher pressure. In a steam engine, the water is often boiled under high pressure, which allows the temperature of the steam to rise above 100°C (the normal boiling point of water at atmospheric pressure).

Correct answer for the Physics SSC CHSL MCQ: Hygrometer

Explanation:
A hygrometer is an instrument used to measure humidity, or the amount of moisture (water vapor) present in the air. Humidity is an important factor in weather forecasting, climate studies, and in many industrial and scientific applications, such as in greenhouses or laboratories. There are different types of hygrometers that use different methods to measure humidity:

1. Mechanical Hygrometers: These use materials such as human hair or special synthetic materials that expand or contract as the humidity changes. The change in length is used to determine the humidity level.
2. Electronic Hygrometers: These use sensors (e.g., capacitive or resistive sensors) that measure changes in the electrical properties of materials as the humidity level varies.
3. Psychrometers: A type of hygrometer that uses two thermometers, one wet and one dry, to calculate the humidity by measuring the difference in temperature between the two.

Other Options:

1. Anemometer: An anemometer is used to measure the wind speed or velocity of air. It typically consists of rotating cups or blades that spin in the wind, and the rate of rotation is used to determine wind speed.
2. Thermometer: A thermometer measures temperature. It can be used to measure both air temperature and the temperature of objects or liquids. There are different types of thermometers, such as mercury thermometers, digital thermometers, and infrared thermometers.
3. Pyrheliometer: A pyrheliometer is an instrument used to measure the solar radiation or solar energy received from the sun. It is typically used in meteorological studies and solar energy research.

Additional Information:

• Importance of Humidity Measurement: Measuring humidity is crucial in many fields such as agriculture, meteorology, and environmental science. High humidity levels can lead to discomfort and health issues, while low humidity can cause dryness in the skin and respiratory issues.
• The relative humidity is commonly measured, which is the amount of moisture in the air relative to the maximum amount of moisture the air can hold at a given temperature. Hygrometers often provide readings in percentage terms.

Correct answer for the Physics SSC CHSL MCQ: Correct answer: Centrifugal force

Explanation:
In a cream separator, centrifugal force is used to separate fat (cream) from milk. The separator spins rapidly, and as a result, the heavier components of the milk, such as skim milk, are pushed towards the outer part of the container, while the lighter cream (which has a higher fat content) moves towards the center. This process is based on the principle of centrifugal force, which acts outward from the center of rotation, causing the separation of the components based on their densities.

Other Options:

1. Cohesive force: Cohesive forces are the forces of attraction between like molecules, such as water molecules sticking together. This force does not play a role in the separation of cream from milk in a cream separator.
2. Gravitational force: While gravity does play a role in the overall behavior of liquids, in the case of a cream separator, it is centrifugal force that causes the cream to be separated, not gravity.
3. Centripetal force: Centripetal force is the force that acts towards the center of a rotating object, and it keeps the particles in their circular path. However, centrifugal force, which is the apparent outward force felt by objects moving in a circular path, is what causes the separation of cream in this case.

Correct answer for the Physics SSC CHSL MCQ: Correct answer: Alternating current only

Explanation:
A transformer works with alternating current (AC) only. The basic principle behind a transformer involves electromagnetic induction, which requires a changing magnetic field. Alternating current naturally produces this changing magnetic field because its direction and magnitude vary continuously with time. This varying magnetic field induces a voltage in the secondary coil, which is how a transformer transfers energy.

In contrast, direct current (DC) produces a constant magnetic field, which does not vary. This lack of variation in the magnetic field means no voltage would be induced in the secondary coil of the transformer, making the transformer ineffective with DC.

Other Options:

1. Direct current only: A transformer does not work with DC because the magnetic field is not varying.
2. Both AC and DC: A transformer only works with AC and not DC.
3. Any signal: A transformer works with AC signals, not just any signal, as it relies on the varying magnetic field produced by alternating current.

Correct answer for the Physics SSC CHSL MCQ: North Pole

Explanation:
The weight of a body on Earth is the force of gravity acting on it, and it is maximum at the poles (both North and South). This happens because Earth is not a perfect sphere but is slightly flattened at the poles due to its rotation. The Earth’s rotation causes a centrifugal force that slightly reduces the effect of gravity at the equator. Therefore, at the equator, the effective gravity is weaker than at the poles.

At the North Pole and South Pole, the centrifugal force due to Earth’s rotation is zero because these points are on the axis of rotation. As a result, the weight is maximized there.

If the mass of the body is m, the force of attraction of the earth, or the weight w of the body, is given by the Newton’s law of gravitation as w = mg, with acceleration due to gravity g \(\displaystyle =\frac{{GM}}{{{{R}^{2}}}}\) where M and R are the mass and radius of the Earth respectively. Since weight of the body is directly proportional to g, the weight of the body is maximum at the centre of the earth and zero at the centre of the earth.

Other Options:

1. South Pole: The weight is also maximum at the South Pole, just like the North Pole, as both are on the Earth’s rotational axis.
2. Equator: The weight is least at the equator due to the centrifugal force caused by Earth’s rotation.
3. Surface: While this refers to the general surface of the Earth, the weight is specifically maximized at the poles (both North and South), not across the entire surface.

Correct answer for the Physics SSC CHSL MCQ: Remote sensing

Explanation:
Remote sensing is the technique of collecting information about an object or area from a distance, typically using satellite or aircraft-based sensors, without making physical contact with it. This method is used to gather data about the Earth’s surface, atmosphere, and oceans, as well as other distant objects like other planets or celestial bodies. Remote sensing can be used to monitor environmental changes, land use, weather patterns, and much more.

Other Options:

1. Remote control: Remote control refers to the operation of a device from a distance, typically using signals like infrared or radio waves, but it does not involve collecting information about an object.
2. Remote accessing: Remote accessing involves accessing and controlling computer systems or networks from a distance, typically through the internet, but it is not related to collecting physical data from an object.
3. Space shuttle: A space shuttle is a spacecraft used for transporting astronauts and cargo into space, but it is not a technique for collecting data remotely.

Correct answer for the Physics SSC CHSL MCQ: Concave

Explanation:
The head mirror used by ENT (Ear, Nose, and Throat) doctors is concave in shape. The concave mirror is used to focus light on a specific area, allowing the doctor to have a well-lit view of the patient’s ear, nose, or throat. The concave shape helps in reflecting and concentrating light onto the desired area for better examination.

Other Options:

1. Convex: A convex mirror diverges light and is not used in head mirrors because it doesn’t focus the light in the way needed for precise examination.
2. Plane: A plane mirror reflects light without focusing it. This type of mirror is not suitable for use in head mirrors for medical examinations.
3. Plano-convex: A plano-convex mirror has one flat side and one convex side, which is not commonly used in head mirrors in ENT practices.

Correct answer for the Physics SSC CHSL Question is  Electrical energy

Explanation:
The direct conversion of solar energy using a photovoltaic (PV) cell (also called a solar cell)results in the production of electrical energy. A photovoltaic cell, commonly known as a solar cell, converts sunlight directly into electricity through the photovoltaic effect. When sunlight strikes the cell, it excites electrons in the material (usually silicon), causing them to flow and create an electric current.

A solar cell (in that its electrical characteristics—e.g. current, voltage, or resistance— vary when light is incident upon it) which, when exposed to light, can generate and support an electric current without being attached to any external voltage source.

Other Options:

1. Optical energy refers to energy in the form of light. While solar cells use light, they convert it into electrical energy, not optical energy.
2. Thermal energy: Solar energy can also be converted to thermal energy using solar thermal collectors, but a photovoltaic cell directly converts it into electrical energy, not thermal.
3. Mechanical energy is typically generated through machines or engines, not directly through a photovoltaic cell.

Correct answer for the Physics SSC CHSL Question is  Equal to the centripetal force

Explanation:
A man inside an artificial satellite feels weightlessness because he and the satellite are in a state of free fall towards the Earth. The force of attraction due to the Earth (gravity) is still acting on the satellite and the person inside it. However, both the satellite and the person are moving with the same acceleration towards the Earth due to gravity, and this results in the sensation of weightlessness.

In the satellite’s circular orbit, the gravitational force that pulls the satellite toward the Earth is balanced by the centripetal force required to keep the satellite in orbit. Since both the satellite and the person inside it are falling together, there is no normal force acting on the person, creating the sensation of weightlessness.

Other Options:

1. Zero at that place: The gravitational force is not zero inside an artificial satellite. In fact, the gravitational force is still present, but the sensation of weightlessness occurs due to the free-fall motion.
2. Balanced by the force of attraction due to the moon: While the moon’s gravitational influence exists, it is much weaker compared to the Earth’s gravitational pull and does not contribute significantly to the sensation of weightlessness in the satellite.
3. Non-effective due to particular design of the satellite: The design of the satellite does not negate the Earth’s gravitational force. The satellite’s design allows it to remain in orbit, but the weightlessness felt by the man is due to the free-fall condition.

Correct answer for the Physics SSC CHSL Question is  Decreases

Explanation:
When a detergent is added to pure water, its surface tension decreases. Detergents are surfactants, meaning they reduce the surface tension of water by disrupting the intermolecular forces between water molecules. This reduction in surface tension allows water to spread more easily and penetrate surfaces better, which is why detergents are effective at cleaning. They help water to wet surfaces and dissolve oils and dirt, which otherwise would be harder to remove due to the higher surface tension of pure water. It happens because the polar end of the soap or detergent is also attracted to the water, thereby decreasing the surface tension.

Correct answer for the Physics SSC CHSL Question is  Ozone

Explanation:
The ozone layer is a region of the Earth’s stratosphere that contains a higher concentration of ozone (O₃) molecules compared to other parts of the atmosphere. The primary function of this layer is to absorb most of the ultraviolet (UV) radiation from the Sun, particularly the harmful UV-B and UV-C rays.

• UV-C rays are the most dangerous, causing significant biological damage, but they are almost completely absorbed by the ozone layer.
• UV-B rays can cause skin cancer, cataracts, and other health problems. The ozone layer absorbs about 90% of UV-B radiation, providing significant protection for life on Earth.
• UV-A rays, which are less harmful, can still penetrate the atmosphere, but their effects are less dangerous compared to UV-B and UV-C.

Without the ozone layer, life on Earth would be much more exposed to the harmful effects of UV radiation, making the ozone layer essential for protecting both human health and the environment.

Other Options:

1. Oxygen: Oxygen (O₂) is a vital component of the atmosphere and supports life, but it does not effectively absorb UV radiation. While oxygen in the upper atmosphere can interact with UV radiation to form ozone, it is the ozone (O₃) molecules that directly absorb the UV radiation.
2. Hydrogen: Hydrogen is a light element that is not abundant in the Earth’s atmosphere and does not play a role in blocking UV radiation. In fact, hydrogen is more relevant in the composition of stars, including the Sun, but not in protecting the Earth from UV rays.
3. Helium: Helium is another light element that exists in trace amounts in the atmosphere, but like hydrogen, it does not contribute significantly to blocking UV radiation.

Correct answer for the Physics SSC CHSL Question is Reflect all the light that reaches them

Explanation:
White clothes are cooler than black ones because they reflect all the light (including heat) that reaches them. When light, including infrared radiation (heat), hits a white surface, most of it is reflected away, and very little is absorbed. This means that white clothes do not absorb as much heat, which keeps them cooler compared to darker colors.

In contrast, black clothes absorb most of the light and heat that reaches them, causing them to warm up quickly. Black surfaces absorb almost all wavelengths of light and convert them into heat, which is why black clothes feel hotter when exposed to sunlight.

Correct answer for the Physics SSC CHSL Question is  Red, Blue, Green

Explanation:
The primary colors in photography (specifically in the additive color model) are Red, Blue, and Green. This model is used in devices like cameras, television screens, and computer monitors, where different amounts of red, green, and blue light are combined to create a full spectrum of colors.

• When red, green, and blue light are mixed in different intensities, they can produce all other colors, including white when all three are combined at full intensity.

In contrast, the subtractive color model (used in printing and mixing paints) uses cyan, magenta, and yellow as the primary colors.

Correct answer for the Physics SSC CHSL Question is  A virtual image

Explanation:
A concave lens (also known as a diverging lens) always forms a virtual image. This type of lens causes parallel light rays to diverge, and when extended backward, the rays appear to come from a single point. The image formed by a concave lens is always virtual, upright, and reduced in size, regardless of the position of the object.

Other Options:

1. A real image: A concave lens never forms a real image. Real images are formed by converging lenses (like convex lenses), not diverging lenses.
2. An image type which depends on object characteristics: While the size and position of the image may depend on the object’s position relative to the lens, a concave lens always forms a virtual image regardless of the object’s characteristics.
3. An image type which depends on lens curvature: The type of image (virtual or real) formed by a concave lens does not depend on its curvature in this case; it always forms a virtual image.

Correct answer for the Physics SSC CHSL Question is  Scattering of shorter wavelengths of sunlight in the atmosphere

Explanation:
The blue color of the sky is due to the scattering of shorter wavelengths of sunlight in the Earth’s atmosphere, a phenomenon known as Rayleigh scattering. This phenomenon was discovered by Lord Rayleigh (John William Strutt) in the 19th century. Sunlight consists of many colors, each with different wavelengths. Blue light has a shorter wavelength compared to other colors like red or yellow. When sunlight enters the Earth’s atmosphere, it interacts with air molecules and small particles, scattering shorter wavelengths of light (blue and violet) much more than the longer wavelengths (red, orange, and yellow). Although both blue and violet light are scattered, the human eye is more sensitive to blue, and the upper atmosphere absorbs some violet light, making the sky appear predominantly blue.

Other Options:

1. Reflection of sunlight: The blue color of the sky is not caused by reflection. Reflection typically occurs on surfaces like water, mirrors, or other objects, not in the atmosphere.
2. Refraction of sunlight: Refraction bends light as it passes from one medium to another, but it does not cause the sky to appear blue. Refraction is responsible for phenomena like rainbows or the bending of light at sunrise or sunset.
3. Scattering of longer wavelengths of sunlight in the atmosphere: The scattering of longer wavelengths (such as red or yellow) does not explain the blue sky. In fact, these wavelengths scatter much less than blue light.

Correct answer for the Physics SSC CHSL Question is Wood is a bad conductor of heat

Explanation:
Metal tea pots have wooden handles because wood is a bad conductor of heat. When a metal tea pot is heated, the metal conducts heat very efficiently, and without a proper insulating handle, it would become too hot to hold. Wood, being a poor conductor of heat, prevents heat from transferring from the hot metal to the handle, making it safer and more comfortable to hold.

Other Options:

1. It prevents electric shock: While it is true that wood is an insulator, the reason for wooden handles in tea pots is to prevent heat transfer, not to prevent electric shock. Electric shock concerns are more relevant in the context of electrical appliances, not in traditional metal tea pots.
2. It gives beauty to the pots: While wood can certainly add aesthetic value to a tea pot, the primary function of the wooden handle is to serve as an insulator, not for decoration.
3. It is hygienic: Wood is not necessarily more hygienic than metal. The main reason for using wood in tea pots is its ability to prevent heat transfer, not because it is more hygienic.

Correct answer for the Physics SSC CHSL Question is Ultra-violet rays

Explanation:
The ozone layer above the Earth’s surface provides a shield against ultraviolet (UV) rays from the Sun. The ozone layer absorbs most of the harmful UV-B and UV-C radiation, which can cause damage to living organisms, including skin cancer and cataracts in humans. While UV-A rays can still reach the Earth’s surface, the ozone layer plays a crucial role in protecting life on Earth from the more harmful types of UV radiation. The Ozone layer absorbs 97–99% of the Sun’s medium-frequency ultraviolet light (from about 200 nm to 315 nm wavelength), which potentially damages exposed life forms on Earth.

Other Options:

1. X-rays: The ozone layer does not block X-rays, as they have much higher energy and are absorbed primarily by the Earth’s atmosphere, but not specifically by the ozone layer.
2. Gamma rays: Similar to X-rays, gamma rays are very high-energy radiation, and their protection comes primarily from the Earth’s atmosphere, not just the ozone layer.
3. Infra-red rays: Infrared radiation is not blocked by the ozone layer. The Earth’s atmosphere absorbs and re-emits some infrared radiation, contributing to the greenhouse effect, but this is not related to the ozone layer.

Correct answer for the Physics SSC CHSL Question is  Law of inertia

Explanation:
Newton’s First Law is also known as the Law of Inertia. It states that an object will remain at rest or move with constant velocity unless acted upon by an external force. This law describes the natural tendency of objects to resist changes in their state of motion, which is referred to as inertia. The law highlights that in the absence of external forces, an object will not change its velocity, whether it is at rest or in motion.

Other Options:

1. Law of moments: The law of moments relates to the principle of equilibrium in physics and states that the sum of moments (force × distance) around any point is zero for an object in rotational equilibrium. This is not related to Newton’s First Law.
2. Law of energy: This refers to principles like the conservation of energy but is not related to Newton’s First Law.
3. Law of momentum: The law of momentum is related to Newton’s Second Law, which states that the change in momentum of an object is equal to the force applied to it. It is not the same as Newton’s First Law.

Correct answer for the Physics SSC CHSL Question is Surface area of the bottom of the vessel

Explanation:
To calculate the pressure at the bottom of a liquid column, the formula used is:

P=ρgh

Where:

• P is the pressure at the bottom of the liquid
• ρ is the density of the liquid
• g is the acceleration due to gravity
• h is the height of the liquid column

From this formula, you can see that the surface area of the bottom of the vessel is not required to calculate the pressure at the bottom. The pressure depends only on the height of the liquid column, the density of the liquid, and the acceleration due to gravity. The surface area of the bottom of the vessel affects the force exerted on the surface, but it does not affect the pressure at a point in the liquid.

Correct answer for the Physics SSC CHSL Question is the temperature inside the earth is higher than the atmospheric temperature

Explanation:
The water from a hand pump is often warmer in winter because the temperature inside the Earth is relatively constant and higher than the atmospheric temperature. In winter, the surface temperature of the Earth can drop significantly, but the ground below the surface maintains a more stable, relatively warmer temperature. When water is pumped from the ground, it has been stored underground where it is shielded from the cold air above, so it comes out warmer compared to the chilly air.

Other Options:

1. Our body is cold in winter and the water appears to be warm: This is not true. The sensation of warmth comes from the actual temperature of the water, not from the body’s perception of it.
2. The pumping process causes friction which warms up the water: While friction does cause heat, it is usually negligible in hand pumps. The warmth of the water is not due to friction.
3. Inside water comes out and absorbs heat from the environment: This is incorrect. The water is already warmer than the outside air when it comes out, so it does not absorb heat from the environment, but rather comes out at a higher temperature due to its underground origin.

Correct answer for the Physics SSC CHSL Question is  Refraction

Explanation:
When you view a water tank from the top, the water appears shallower than it actually is due to refraction. Refraction occurs when light passes from one medium to another, such as from air (less dense) to water (more dense). The light bends as it enters the water, and because the light rays are bent towards the normal, the depth of the water appears less than its actual value. This phenomenon is explained by Snell’s Law, which describes how light bends when it enters a different medium.

Other Options:

1. Rectilinear propagation of light: The rectilinear propagation of light refers to the idea that light travels in straight lines in a uniform medium. While light generally travels this way, it doesn’t explain why the water appears shallower. This effect is due to refraction.
2. Reflection occurs when light bounces off a surface, but it doesn’t cause the water to appear shallower. Reflection would cause you to see the surface of the water, but not affect its depth perception.
3. Total internal reflection occurs when light is completely reflected inside a medium (such as light traveling from water to air) and does not exit the medium. It is not the reason the water appears shallower when viewed from the top.

Correct answer for the Physics SSC CHSL Question is Air to water

Explanation:
Total internal reflection occurs when light passes from a denser medium to a rarer medium at an angle greater than the critical angle for the pair of materials. The light is completely reflected back into the denser medium, rather than refracted into the rarer medium.

Total internal reflection is an optical phenomenon that happens when a ray of light strikes a medium boundary at an angle larger than a particular critical angle with respect to the normal to the surface. This can only occur where light travels from a medium with a higher [n1 =higher refractive index] to one with a lower refractive index [n2 =lower refractive index]. Total internal reflection can be seen at the air-water boundary.

Correct answer for the Physics SSC CHSL Question is  Just before it touches the ground

Explanation:
When a stone is dropped from a height, it begins with zero kinetic energy because it starts at rest. As it falls under the influence of gravity, its potential energy (due to height) is converted into kinetic energy. The kinetic energy increases as the stone gains speed during the fall.

• The kinetic energy is at its maximum just before the stone touches the ground because this is when the stone has reached its maximum speed, and most of the potential energy has been converted into kinetic energy.
• At the moment just after it is dropped, the kinetic energy is zero because the stone is initially at rest.
• When the stone is halfway down, it has a mix of potential and kinetic energy, but the kinetic energy is still less than it is just before it hits the ground.
• When the stone touches the ground, the kinetic energy is converted into other forms like sound and heat, and thus it becomes zero at the point of impact.

Correct answer for the Physics SSC CHSL Question is  All wavelengths

Explanation:
A black body is an idealized object that can absorb all wavelengths of electromagnetic radiation. It is a perfect absorber and emitter of radiation. A black body absorbs radiation across the entire electromagnetic spectrum, from lower wavelengths (such as infrared) to higher wavelengths (such as ultraviolet and even visible light). Because of this characteristic, a black body is often used as a model in studies of thermal radiation.

In addition to absorbing all wavelengths, a perfect black body also emits radiation efficiently at all wavelengths according to its temperature, a phenomenon described by Planck’s law.

Correct answer for the Physics SSC CHSL Question is Pascal’s Law

Explanation:
Pascal’s Law states that any change in pressure applied to an enclosed fluid is transmitted undiminished to all portions of the fluid and to the walls of its container. This principle is the foundation of hydraulic systems. In such systems, when a force is applied to a fluid in a confined space, the pressure is uniformly distributed in all directions, allowing for the amplification of force. This enables hydraulic machines to use a small amount of force to move a larger object, as seen in hydraulic presses, lifts, and brakes.

For example, in a hydraulic press, a small force applied to a small piston results in a larger force being exerted by a large piston because of the uniform pressure distribution across the fluid.

Other Options:

1. Newton’s laws of motion describe the relationship between the motion of an object and the forces acting on it. While Newton’s laws apply to various mechanical systems, they are not directly related to the functioning of hydraulic machines, which rely on the transmission of pressure in a fluid.
   • First law (Law of inertia): Describes an object’s tendency to stay at rest or in uniform motion unless acted upon by a force.
   • Second law (F = ma): Describes how the acceleration of an object is proportional to the force applied and inversely proportional to its mass.
   • Third law (Action and reaction): States that for every action, there is an equal and opposite reaction.
2. Joule’s law relates to the heat generated when an electric current passes through a conductor. It is used to calculate the energy dissipated as heat in electrical circuits but has no relevance to the operation of hydraulic machines. Joule’s law is more related to electrical systems than to fluid dynamics or mechanical advantage in hydraulic systems.
   • Formula: Q=I²Rt, where Q is the heat produced, III is the current, R is the resistance, and t is the time the current flows.
3. Floatation Law: The principle related to buoyancy or flotation is Archimedes’ principle, not a “floatation law.” Archimedes’ principle states that any object submerged in a fluid experiences an upward buoyant force equal to the weight of the fluid displaced by the object. This principle explains why objects float or sink in water, but it does not pertain to hydraulic systems or pressure transmission.
   • Archimedes’ principle is primarily used to understand buoyancy in fluids and does not have a direct role in the operation of hydraulic systems.

Correct answer for the SSC CHSL Physics question is Surface area of the liquid

Explanation:
The pressure at a given depth in a liquid depends on the density of the liquid, the depth (height) of the liquid, and the acceleration due to gravity. These factors directly influence the amount of pressure exerted by the liquid at that depth.

However, the surface area of the liquid does not affect the pressure at a specific depth. Pressure is a scalar quantity, and it is uniform across all points at the same depth, regardless of the surface area. Therefore, surface area is not a factor in determining the pressure at that depth.

Correct answer for the SSC CHSL Physics question is The temperature inside the Earth is higher than the atmospheric temperature

Explanation:
The water from a hand pump feels warm in winter because the temperature inside the Earth is relatively constant and higher than the cold atmospheric temperature. The Earth’s interior remains warmer than the surface during winter, and water from deep underground comes to the surface at a temperature closer to the Earth’s natural temperature, which is warmer than the cold air outside. This is why water from hand pumps, especially those drawing from deeper wells or underground sources, feels warmer in the colder months.

Other Options:

1. Our body is cold in winter and the water appears to be warm: This is incorrect because the water is genuinely warmer than the outside temperature, not just perceived as warm due to our body temperature.
2. The pumping process causes friction which warms up the water: While friction might cause slight heating, this is not the primary reason the water feels warm. The temperature difference is primarily due to the temperature of the water from underground sources.
3. Inside water comes out and absorbs heat from the environment: Water from underground does not absorb heat from the environment immediately upon coming out. The temperature of the water is already higher than the surrounding air, so it does not need to absorb heat from the environment.

Answer is Option (4) for the SSC CHSL Physics MCQ

Correct answer for the SSC CHSL Physics question is Metal is a better conductor of heat than wood

Explanation:
When you place a metal spoon and a wooden spoon in the same water, the metal spoon feels colder because metal is a better conductor of heat. This means it quickly transfers heat from your hand, making it feel colder compared to the wooden spoon, which does not conduct heat as well. As a result, the metal spoon draws heat from your hand faster than the wooden one, making it feel colder.

Other Options:

1. Metal has a higher density than wood: Although metal does have a higher density, this factor does not directly explain why the metal spoon feels colder.
2. Wood absorbs heat from the hand, but it is not a good conductor, so it doesn’t make the spoon feel colder as rapidly as metal.
3. Wood reflects heat better than metal: Wood does not reflect heat better than metal; in fact, it tends to insulate, which is why it feels warmer than metal.

Correct answer for the SSC CHSL Physics question is The Earth’s surface would receive harmful ultraviolet radiation

Explanation:
If the ozone layer were to completely deplete, there would be nothing to block the harmful ultraviolet (UV) radiation from the Sun. This would result in a significant increase in the amount of UV-B and UV-C radiation reaching the Earth’s surface, leading to serious health consequences like skin cancer, cataracts, weakened immune systems, and damage to ecosystems. The ozone layer serves as a protective barrier, absorbing most of this harmful radiation.

Other Options:

1. No change in the temperature of the Earth: If the ozone layer depletes, the UV radiation reaching the Earth’s surface would increase, which could lead to warming of the atmosphere, not leaving the temperature unchanged.
2. The Earth’s atmosphere would become thicker: The depletion of the ozone layer does not affect the thickness of the atmosphere in this way. Atmospheric composition would change, but not in this manner.
3. The ozone would be replaced by nitrogen in the atmosphere: Nitrogen makes up most of the atmosphere naturally, but it does not replace the ozone layer in terms of protecting against UV radiation. Nitrogen does not absorb harmful UV rays.

Correct answer for the SSC CHSL Physics question is It has high specific heat

Explanation:
Water is used in hot water bags because it has a high specific heat capacity. This means that water can absorb a large amount of heat energy before its temperature increases significantly. When water is heated, it can store and retain heat for a long period, releasing it gradually, which makes it effective for use in hot water bags. This helps in providing a sustained heat source for comfort or therapeutic purposes.

The specific heat is the amount of heat per unit mass required to raise the temperature by one degree Celsius. The specific heat of water is 1 calorie/gram °C = 4.186 joule/gram °C which is higher than any other common substance. As a result, water plays a very important role in temperature regulation.

Correct answer for the SSC CHSL Physics question is Lack of adhesive force

Explanation:
Water drops cannot stick to an oily surface because of the lack of adhesive force between the water and the oil. Adhesive forces are the attractive forces between different substances, such as water and oil. Water molecules tend to bond more strongly with each other (due to hydrogen bonding), while the interaction between water and oil is weaker. As a result, the water droplets tend to remain separate and do not spread out or stick to the oily surface.

The water molecules stick together tightly and does not mix with the oil because water molecules are attracted to each other very strongly, forming an invisible “skin” of surface tension around each drop.

Correct answer for the SSC CHSL Physics question is Brittleness

Explanation:
Nonmetals generally exhibit brittleness when solid. Unlike metals, which are usually malleable and ductile (can be hammered into sheets or stretched into wires), nonmetals tend to break or shatter when subjected to stress. This is due to the relatively weak forces between their atoms in the solid state. Nonmetals have a wide variety of physical and chemical properties, but brittleness is a common characteristic, especially in their solid form.

Other Options:

1. Conductivity: Nonmetals are generally poor conductors of electricity and heat, unlike metals, which are good conductors.
2. Ductility (the ability to be drawn into wires) is a property typical of metals, not nonmetals.
3. Malleability (the ability to be hammered into thin sheets) is also characteristic of metals, not nonmetals.

Correct answer for the SSC CHSL Physics question is a – 1, b – 3, c – 4, d – 2

Explanation:
The correct matching between the processes and the changes is:

a. Evaporation – 1. Liquid into gas: Evaporation is the process where liquid turns into gas at the surface.

b. Sublimation – 3. Solid into gas: Sublimation is the process where a solid directly converts into gas, bypassing the liquid state (like dry ice turning into carbon dioxide gas).

c. Freezing – 4. Liquid to Solid: Freezing is the process where a liquid turns into a solid when the temperature decreases.

d. Melting – 2. Solid into liquid: Melting is the process where a solid turns into a liquid when it is heated.

Correct answer for the SSC CHSL Physics question is Air Pollutants

Explanation:
An electrostatic precipitator is a device used to control air pollutants, particularly those in the form of particulate matter (like dust, smoke, and other airborne particles). It works by applying a high voltage to the particles in the air, causing them to become electrically charged. These charged particles are then attracted to and collected on oppositely charged plates, effectively removing them from the air and reducing pollution.

Other Options:

1. Chemical Pollutants: While electrostatic precipitators can remove particulate matter that may be associated with chemical pollutants, they are not designed to directly control chemical pollutants.
2. Radio-active Pollutants: Electrostatic precipitators are not designed to control radioactive pollutants, which require specialized filters and shielding.
3. Water Pollutants: Electrostatic precipitators are used for air purification and are not applicable to water pollutants.

Correct answer for the SSC CHSL Physics question is Microphone

Explanation:
The conversion of sound energy into electrical energy is done by a microphone. A microphone works by capturing sound waves (which are vibrations in the air) and converting them into electrical signals. This is typically done through a diaphragm that moves in response to sound pressure, generating an electrical current or voltage that corresponds to the sound wave.

Other Options:

1. Solar cell: A solar cell converts solar energy (light) into electrical energy, not sound energy.
2. Gramophone: A gramophone is an older device that converts sound energy into mechanical energy, not electrical energy.
3. Loudspeaker: A loudspeaker works the opposite way — it converts electrical energy into sound energy, not the other way around.

Correct answer for the SSC CHSL Physics question is Avoid the tracks being distorted due to seasonal temperature variation

Explanation:
A small gap is left at the joints of railway tracks to avoid distortion of the tracks due to seasonal temperature variations. Metal, including the steel used in railway tracks, expands when heated and contracts when cooled. If there were no gaps at the joints, the expansion of the rails in hot weather could cause them to buckle or warp, potentially leading to accidents. The small gaps allow for the necessary expansion and contraction of the rails without causing damage to the track structure.

Other Options:

1. Avoid the heating of tracks to high temperature: The gap does not prevent the tracks from heating to high temperatures; it simply allows for expansion when the tracks do heat up.
2. Control the speed of train: The gaps in the tracks have no effect on controlling the speed of a train.
3. Keep the rails equidistant: The gaps do not affect the distance between the rails; their purpose is to allow for thermal expansion.

Correct answer for the SSC CHSL Physics question is More thermal conductivity

Explanation:
For a metal to be used as a cooking material, it is important that it has more thermal conductivity. This allows the metal to quickly and evenly transfer heat to the food being cooked. Metals with high thermal conductivity, such as copper and aluminum, are excellent choices for cooking utensils like pans and pots, as they heat up quickly and distribute heat evenly across the surface. This ensures efficient cooking.

Other Options:

1. More specific heat: Specific heat refers to the amount of heat required to change the temperature of a substance. While a higher specific heat would allow the material to retain heat, it doesn’t necessarily make it suitable for cooking. A metal with high specific heat might take longer to heat up, which is not ideal for cooking.
2. Less thermal conductivity: Less thermal conductivity would mean that the metal does not efficiently transfer heat, which would make it unsuitable for cooking, as it would not heat evenly or quickly.
3. Less electrical conductivity: Electrical conductivity is not a significant factor in determining whether a metal is suitable for cooking. The ability to conduct heat (thermal conductivity) is far more important.

Correct answer for the SSC CHSL Physics question is 0.0002 µ bar

Explanation:
The least audible sound for most human ears corresponds to the threshold of hearing, which is the quietest sound that can typically be heard by the average person. This is usually around 0.0002 µ bar, or 20 μPa (micropascals), which is the reference level for the faintest sound intensity that can be detected by the human ear. This is often referred to as the threshold of hearing.

Other Options:

1. 10.0 µ bar: This is much louder than the threshold of hearing. It is above the quietest sound that the average human ear can detect.
2. 0.005 µ bar: This is also louder than the least audible sound and not the correct threshold of hearing.
3. 5.0 µ bar: This is also louder than the least audible sound, and not the correct threshold of hearing.

Correct answer for the SSC CHSL Physics question is bsolute humidity

Explanation:
Absolute humidity refers to the amount of water vapor (in grams) present in a given volume of air (usually expressed in grams per cubic meter). It measures the actual quantity of water vapor in the air, irrespective of the air’s temperature.

Other Options:

1. Mixing ratio: The mixing ratio refers to the mass of water vapor per unit mass of dry air, not the volume of air.
2. Relative humidity: Relative humidity is the ratio of the current absolute humidity to the maximum possible humidity at a given temperature, expressed as a percentage. It does not represent the actual amount of water vapor.
3. Specific humidity: Specific humidity refers to the mass of water vapor per unit mass of air (both dry and wet), typically expressed in grams per kilogram, and is not directly related to the volume of air.

Correct answer for the SSC CHSL Physics question is Inertia of motion

Explanation:
When a running car stops suddenly, the passengers tend to lean forward due to the inertia of motion. Inertia is the property of an object that resists changes in its state of motion. Since the passengers are initially in motion with the car, when the car stops suddenly, their bodies tend to continue moving forward due to their inertia. This is because they want to maintain the same speed and direction as they were before the car stopped.

Other Options:

1. Centrifugal force: Centrifugal force is a pseudo-force that appears when an object moves in a circular path and is not relevant to this situation. It doesn’t cause passengers to lean forward when the car stops suddenly.
2. Inertia of rest: The inertia of rest refers to the tendency of an object to remain at rest unless acted upon by an external force. It is not applicable here because the passengers are already in motion, not at rest.
3. Gravitational force: Gravitational force is the force that attracts objects toward the center of the Earth. It does not directly cause passengers to lean forward in the event of a sudden stop.

Correct answer for the physics questions for ssc chsl is Mica

Explanation:
Mica is a good conductor of heat but a poor conductor of electricity. Mica is commonly used in electrical and electronic equipment as an insulator because it does not conduct electricity well. However, it has excellent heat resistance and can transfer heat effectively, making it useful in devices that need heat dissipation but should not allow the passage of electric current.

Other Options:

1. Asbestos: Asbestos is a good insulator for both heat and electricity, so it does not fit the criteria of being a good heat conductor but a bad electrical conductor.
2. Celluloid: Celluloid is a poor conductor of both heat and electricity and is not suitable for applications that require heat conduction.
3. Paraffin wax: Paraffin wax is also a poor conductor of both heat and electricity and is used primarily as an insulating material.

Correct answer for the physics questions for ssc chsl is Copper

Explanation:
For copper, the resistance decreases with an increase in temperature. Copper is a conductor, and like most conductors, its resistance increases with temperature. However, the increase in temperature generally leads to an increase in atomic vibrations in the copper, which, in turn, leads to an increase in resistance. The statement in the question suggests a special case, and copper tends to exhibit lower resistance as the temperature increases due to its excellent conductivity properties.

Other Options:

1. Pure silicon: Silicon is a semiconductor, and its resistance generally increases with temperature.
2. Nichrome: Nichrome is a resistive alloy that is designed to have a high resistance, and its resistance increases with temperature.
3. Platinum: Platinum is a metal, and its resistance increases with temperature, similar to other metals.

Correct answer for the physics questions for ssc chsl is Surface tension of water

Explanation:
A solid needle placed horizontally on the surface of water floats due to the surface tension of water. Surface tension is the property of a liquid that allows it to resist external forces, creating a sort of “skin” on the surface. This tension is strong enough to support objects that are denser than water, like a needle, if the object is small enough and placed gently. The cohesive forces between water molecules at the surface form a “film” that holds the needle up.

Other Options:

1. Capillary action: Capillary action refers to the ability of a liquid to flow in narrow spaces against gravity (like in a thin tube), but it is not the cause of the needle floating on water.
2. Water pressure: Water pressure applies at all depths of the water and contributes to buoyancy, but it is not the reason the needle floats horizontally on the surface.
3. Viscosity of water: Viscosity refers to the resistance of a liquid to flow. While it affects the movement of objects through water, it is not the cause of the needle floating on the surface.

Correct answer for the physics questions for ssc chsl is Is a bad conductor of heat so only inner surface expands

Explanation:
When hot liquid is poured into a thick glass tumbler, it cracks due to the fact that glass is a poor conductor of heat. When hot liquid is poured into the tumbler, the inner surface of the glass heats up quickly, causing it to expand, while the outer surface (which is not heated as quickly) remains relatively cooler and does not expand as much. This difference in expansion between the inner and outer surfaces creates tensile stress, and if the stress is too great, the glass cracks.

Other Options:

1. Has high temperature coefficient of expansion: Glass has a relatively low temperature coefficient of expansion, meaning it does not expand much with temperature changes. This is not the cause of cracking.
2. Has a very low specific heat: Specific heat refers to the amount of heat required to raise the temperature of a substance. While glass may have a low specific heat, this does not directly cause the cracking when hot liquid is poured into it.
3. Has low temperature coefficient of expansion: While glass does have a relatively low temperature coefficient of expansion, it is the uneven heating of the glass (due to poor heat conduction) that causes the cracking, not the coefficient of expansion itself.

Correct answer for the physics questions for ssc chsl is Renewable natural resource

Explanation:
Hydroelectric power is considered a renewable natural resource because it relies on the flow of water (usually from rivers or dams) to generate electricity. As long as water is available, it can be continuously replenished through the natural water cycle (rain, rivers, etc.), making it a sustainable and renewable source of energy. Unlike fossil fuels, which are finite, hydroelectric power does not deplete any resource when it is used.

Other Options:

1. Non-renewable natural resource: This would apply to resources like coal, oil, and natural gas, which are finite and cannot be replenished in a human lifetime.
2. A mixture of renewable and non-renewable natural resource: This does not apply to hydroelectric power, as it is entirely based on renewable water sources.
3. Neither renewable nor non-renewable resource: This would apply to resources that do not fall into either category, but hydroelectric power is clearly renewable.

Correct answer for the physics questions for ssc chsl is Capillary action

Explanation:
The oil in the wick of an oil lamp rises up due to capillary action. This occurs because the oil is drawn into the small pores of the wick due to the adhesive forces between the oil molecules and the fibers of the wick, combined with the cohesive forces between the oil molecules. The narrow spaces in the wick create a capillary effect that allows the oil to travel upward against gravity. This process is crucial for supplying oil to the flame, where it evaporates and burns.

Other Options:

1. Low viscosity of oil: While the viscosity of oil may affect how easily it flows, it is not the main reason the oil rises in the wick. The primary reason is capillary action, not viscosity.
2. Gravitational force: Gravitational force acts downward, and while it plays a role in the oil’s movement, the oil rises against gravity due to capillary action, not because of gravity itself.
3. Pressure difference: A pressure difference is not the main cause of the oil rising in the wick; it is the capillary action that draws the oil upward.

Correct answer for the physics questions for ssc chsl is A sphere has the least surface area for a given volume

Explanation:
A drop of liquid assumes a spherical shape because a sphere has the least surface area for a given volume. This minimizes the surface energy, as the surface area is minimized for a given amount of liquid. In liquids, the molecules are attracted to each other by cohesive forces, and the liquid tries to reduce the surface area to minimize energy. A sphere provides the most efficient configuration for this purpose, where the surface area is minimal relative to its volume.

Other Options:

1. Intermolecular forces are strong in liquids: While strong intermolecular forces do play a role in the formation of drops, it is the geometry of the sphere that minimizes the surface area and energy, not just the strength of intermolecular forces.
2. A sphere has the largest surface area for a given volume: This is incorrect. The sphere actually has the least surface area for a given volume, which is why a drop of liquid forms a sphere.
3. Intermolecular forces are weak in liquids: While weaker intermolecular forces would affect the behavior of the liquid, the shape of a drop is more about minimizing surface area and surface energy than the strength of these forces.

Correct answer for the physics questions for ssc chsl is Increases

Explanation:
When cream is removed from milk, the remaining liquid is denser than the original mixture. This is because cream is made up of fat, which is less dense than the other components in milk (like water, proteins, and minerals). Removing the cream reduces the fat content, which leads to a higher concentration of denser components in the remaining milk, thus increasing its overall density.

The density of pure fresh milk being on the average 1.032, while the density of fat globules is about 0.86. It follows that the removal of cream will increase the density, while the addition of water will decrease it.

Other Options:

1. Decreases: This would be the case if you added less dense substances to the milk, but removing the less dense cream actually increases the density.
2. Remains the same: The density of the milk changes when cream is removed because the fat content is reduced, so the density does not remain the same.
3. May increase or decrease: The density of the milk always increases when cream is removed because fat is less dense than the other components in milk.

Correct answer for the physics questions for ssc chsl is It forms erect (upright) image

Explanation:
Convex mirrors are used as rear-view mirrors in vehicles like motorcycles for several reasons:

• They form an erect (upright) image, which makes it easier and safer for the driver to view traffic behind them.
• Convex mirrors provide a wider field of view because they diverge light rays, allowing the driver to see more area behind the vehicle.
• They form a smaller image of the object, which helps in showing a larger area, but this smaller image is still upright.

Correct answer for the physics questions for ssc chsl is iincreases with depth of the wall

Explanation:
The pressure exerted by a liquid at a given depth is directly proportional to the depth of the liquid. The pressure on the wall of a dam increases as the depth increases because pressure is given by the formula:

P=ρgh

Where:

• P is the pressure,
• ρ is the density of the liquid (in this case, water),
• g is the acceleration due to gravity, and
• h is the depth of the water.

Since the depth is greater at the bottom of the dam, the pressure is higher there, and hence, the wall must be thicker at the bottom to withstand this greater pressure.

Correct answer for the physics questions for ssc chsl is Compact fluorescent lamp

Explanation:
The full form of CFL is Compact Fluorescent Lamp. CFLs are energy-efficient light bulbs that use fluorescent technology in a compact design. These lamps are much more energy-efficient than traditional incandescent bulbs and consume less power while providing the same amount of light. CFLs work by passing an electric current through a gas, which then produces ultraviolet light. This light interacts with a fluorescent coating inside the lamp, producing visible light.

Correct answer for the physics questions for ssc chsl is It is directly proportional to the area of cross-section of wire

Explanation:
The resistance of a wire is influenced by several factors, and the relationship can be described by the formula:

R = ρ(L/A)

Where:

• R is the resistance,
• ρ is the resistivity of the material (depends on the material),
• L is the length of the wire,
• A is the cross-sectional area of the wire.

Based on this formula:

(1) The resistance does depend on the material of the wire. Different materials have different resistivities.

(2) Resistance is directly proportional to the length of the wire, meaning that as the length increases, resistance increases.

(3) Resistance is inversely proportional to the area of the cross-section. This means that as the area of the wire increases, the resistance decreases, which is opposite to what is stated in option (3).

(4) The resistance of metallic wires typically increases with temperature. As temperature increases, the vibrations of atoms in the wire increase, making it harder for electrons to flow, which increases resistance.

Thus, the false statement is: “It is directly proportional to the area of cross-section of the wire”. In reality, resistance is inversely proportional to the area.

The property of conductor due to which it opposes the flow of current through it is called Resistance. It is numerically equal to the ratio of potential difference across its ends to the current flowing through it. The SI unit of resistance is ohm.

Correct answer for the physics questions for ssc chsl is Microwave

Explanation:
Microwave radiation is primarily used for satellite communication. Microwaves are a type of electromagnetic radiation with wavelengths ranging from 1 millimeter to 1 meter. They are ideal for satellite communication because they can penetrate the atmosphere without significant interference. The frequency bands used for satellite communication fall within the microwave spectrum, specifically in the C-band, Ku-band, and Ka-band.

Other Options:

1. Ultraviolet (UV): UV radiation has higher energy and shorter wavelengths than microwaves, making it unsuitable for long-range communication, as it would be absorbed by the Earth’s atmosphere.
2. Infrared (IR): Infrared radiation is used for communication over shorter distances, such as remote controls and certain optical communication systems, but not for satellite communication.
3. Millimeter wave: While millimeter waves (a subset of microwaves) are used in some high-frequency communication systems, microwaves in general are the primary choice for satellite communication.

Correct answer for the physics questions for ssc chsl is Photovoltaic effect

Explanation:
Solar cells work on the principle of the photovoltaic effect, which is the process where light energy (photons) is converted into electrical energy in a material (typically a semiconductor like silicon). When light strikes the surface of the solar cell, it excites electrons in the material, creating electron-hole pairs. These free electrons are then collected by the cell and used to generate an electric current.

Other Options:

1. Photoelectric effect: The photoelectric effect refers to the phenomenon where light knocks electrons out of a material, but it is more commonly associated with the generation of current in a vacuum tube, not the conversion of light to electricity in solar cells.
2. Photoconductive effect: The photoconductive effect occurs when the electrical conductivity of a material changes upon exposure to light. While this effect is important in some types of light sensors, it is not the main principle behind solar cells.
3. Photosynthesis is the process by which plants convert light energy into chemical energy. This is unrelated to how solar cells convert light into electrical energy.

Correct answer for the physics questions for ssc chsl is Surface tension

Explanation:
Materials for rainproof coats and tents owe their waterproof properties to surface tension. Surface tension is the force that acts at the surface of a liquid, making it behave like a stretched elastic membrane. When water comes into contact with these materials, the surface tension causes the water droplets to bead up and roll off, rather than being absorbed by the fabric. Waterproof fabrics typically have a hydrophobic coating, which enhances this effect by repelling water, allowing the material to remain dry.

Other Options:

1. Viscosity: Viscosity refers to the resistance of a fluid to flow. While it plays a role in how thick or thin a liquid is, it is not related to the waterproof properties of materials like raincoats or tents.
2. Specific gravity: Specific gravity is the ratio of a substance’s density compared to the density of water. It does not affect the waterproof nature of materials.
3. Elasticity: Elasticity refers to a material’s ability to return to its original shape after being stretched or compressed. While it may be important for the durability and flexibility of rainproof fabrics, it is not responsible for their waterproof properties.

Correct answer for the ssc chsl physics questions is Gamma-rays and ultraviolet region

Explanation:
X-rays are a form of electromagnetic radiation with wavelengths that are shorter than ultraviolet (UV) rays but longer than gamma rays. The electromagnetic spectrum consists of various types of radiation, categorized by wavelength and frequency.

• Gamma rays have the shortest wavelengths (less than 10 picometers) and the highest frequencies in the electromagnetic spectrum. These rays are produced by nuclear reactions and certain radioactive materials.
• X-rays have wavelengths between 0.01 to 10 nanometers, and their frequencies are higher than ultraviolet but lower than gamma rays.
• Ultraviolet (UV) radiation lies just below visible light in terms of wavelength (10 nm to 400 nm). UV rays have shorter wavelengths than visible light but longer than X-rays.

X-rays are widely used in medical imaging and industrial applications due to their ability to penetrate materials and produce detailed images of the inside of objects.

Other Options:

1. Ultraviolet and visible region: The ultraviolet region has wavelengths shorter than visible light (from 10 nm to 400 nm), while X-rays have even shorter wavelengths. They are not between ultraviolet and visible light.
2. Visible and infra-red region: The infrared (IR) region has longer wavelengths (700 nm to 1 mm) than visible light. X-rays have much shorter wavelengths and do not lie between visible and infrared radiation.
3. Short radio waves and long radio waves: Radio waves have wavelengths ranging from 1 millimeter to 100 kilometers, much longer than the wavelengths of X-rays, which are in the nanometer range. Hence, X-rays do not lie between short and long radio waves.

Thus, X-rays lie between gamma-rays and the ultraviolet region in the electromagnetic spectrum.

Correct answer for the ssc chsl physics questions is Refraction of light by atmosphere

Explanation:
A star appears to twinkle in the sky because of the refraction of light as it passes through the Earth’s atmosphere. The Earth’s atmosphere is made up of layers of air with varying densities, and as light from the star travels through these layers, it bends (refracts). Since the air density changes due to temperature variations and other factors, the light from the star is refracted in different directions, causing the star to appear to change in brightness and position. This effect is called stellar scintillation and is responsible for the twinkling of stars.

Other Options:

1. Scattering of light by atmosphere: Scattering is responsible for phenomena like the blue color of the sky, but it does not explain why stars twinkle. Scattering affects light that travels through the atmosphere but not light from distant stars in the same way.
2. Reflection of light by atmosphere: Reflection occurs when light bounces off a surface, but this is not responsible for the twinkling effect. Stars do not reflect light from the atmosphere in this way.
3. Diffraction of light by atmosphere: Diffraction occurs when light bends around obstacles or passes through small openings, but it does not cause the twinkling effect in stars.

Correct answer for the ssc chsl physics questions is The rubber ball suffers greater change in momentum

Explanation:
When a metal ball and a rubber ball of the same mass strike a wall normally with the same velocity, the behavior of the two balls is different:

• The rubber ball rebounds after hitting the wall, meaning it undergoes a change in direction and its velocity changes significantly.
• The metal ball does not rebound, which means it comes to a complete stop, and its velocity changes to zero.

The change in momentum is given by the formula:

Δp=m(v_f−v_i)

Where:

• Δp is the change in momentum,
• m is the mass of the ball,
• v_f is the final velocity,
• v_i​ is the initial velocity.

For the rubber ball, the velocity changes direction, so the change in momentum is greater because the ball rebounds (with a velocity in the opposite direction).
For the metal ball, the ball comes to a stop, so the change in momentum is smaller because its final velocity is zero, and the direction doesn’t change.

Since the rubber ball rebounds and the metal ball does not, the rubber ball suffers a greater change in momentum.

As per the question, the rubber ball rebounds while the metal ball does not. So if m and v be the mass and velocity respectively, the change in momentum of rubber ball = 2 mv (in magnitude).

However, the change in momentum of the metal ball = mv.

The rubber ball suffers almost twice the change in momentum as experienced by the metal ball.

Correct answer for the ssc chsl physics questions is Basic unit of nervous system

Explanation:
A neuron is the basic unit of the nervous system. Neurons are specialized cells responsible for transmitting information throughout the body. They communicate with each other through electrical and chemical signals, allowing for processes like thinking, movement, sensation, and coordination. Neurons are fundamental to the functioning of the brain, spinal cord, and nerves.

Other Options:

1. Basic unit of energy: This is incorrect. The basic unit of energy is the joule, not a neuron.
2. Particle released during radioactivity: Neutrons, not neurons, are released during some types of radioactive decay, particularly in processes like fission.
3. The anti-particle of a neutron is called an antineutron, not a neuron.

Correct answer for the ssc chsl physics questions is

The twinkling of stars and variation in size of the Sun are due to atmospheric refraction of light. Besides, refraction is also responsible for the sun to look during sunset and sunrise. It is also responsible for the sun becoming two or three minutes before actual sunrise. The sun appears higher or lower in the sky due to the changing position of the Earth relative to the Sun.

Correct answer for the ssc chsl physics questions is de Broglie waves

Explanation:
Matter waves refer to the de Broglie waves, which are a fundamental concept in quantum mechanics. According to Louis de Broglie, particles like electrons and other matter particles exhibit wave-like behavior. This wave-particle duality is a key principle in quantum theory. De Broglie proposed that every moving particle has an associated wave, and the wavelength (λ) of this wave is related to the particle’s momentum (p) by the equation:

λ = h/p​

Where:

• h is Planck’s constant,
• p is the momentum of the particle.

These matter waves are not electromagnetic waves, but rather waves associated with particles that exhibit both particle and wave properties.

Other Options:

1. Electromagnetic waves: Electromagnetic waves (like light, radio waves, etc.) are not matter waves; they consist of oscillating electric and magnetic fields.
2. Transverse waves: While de Broglie waves can be described mathematically in terms of wave functions, they are not necessarily transverse waves like light waves. In fact, matter waves are not defined by their physical displacement as in the case of transverse or longitudinal waves.
3. Longitudinal waves: Longitudinal waves are waves where the displacement of the medium is in the direction of propagation, like sound waves. Matter waves do not fit this description.

Correct answer for the ssc chsl physics questions is Centrifugal force

Explanation:
When milk is churned vigorously, the cream separates out due to the centrifugal force. During churning, the milk is subjected to a rapid rotation, causing the denser components (like water and other liquids) to move toward the center while the lighter components (like fat, which makes up the cream) are pushed outward, away from the center. This outward force is known as centrifugal force, and it causes the cream to separate from the rest of the milk.

Other Options:

1. Centripetal force: Centripetal force acts inward toward the center of a circular path, which helps keep an object in its circular motion, but it is not responsible for the separation of cream from milk.
2. Gravitational force: Gravitational force affects all objects but does not play a role in separating cream from milk during churning. Gravity is responsible for holding the liquid in the churn, but it doesn’t separate the cream.
3. Frictional force: Frictional force is involved in the churning process as it resists motion between the churn and the milk, but it does not cause the cream to separate. The key factor is the centrifugal force that occurs due to the rotation.

Correct answer for the ssc chsl physics questions is Have large coefficient of expansion

Explanation:
Gas thermometers are more sensitive than liquid thermometers because gases have a larger coefficient of expansion compared to liquids. This means that for a given temperature change, the volume of a gas changes more significantly than that of a liquid. As a result, even small temperature changes cause a noticeable change in the volume of the gas, making gas thermometers highly sensitive and effective at detecting temperature variations.

Other Options:

1. Are lighter: While gases are lighter than liquids, this factor does not contribute to the increased sensitivity of gas thermometers. The sensitivity primarily depends on the coefficient of expansion.
2. Have low specific heat: Gases generally have a lower specific heat compared to liquids, meaning they require less heat to raise their temperature. However, this does not directly explain the higher sensitivity of gas thermometers.
3. Have high specific heat: Gases typically have lower specific heat compared to liquids, and this does not make them more sensitive. The higher sensitivity is due to the large coefficient of expansion.

Correct answer for the ssc chsl physics questions is 1 : 1

Explanation:
Let’s break down the problem step by step:

When the man throws the two stones, both are thrown with the same initial speed but in opposite directions.

1. Stone thrown upwards: The stone is thrown vertically upwards with a certain initial speed. After it reaches its maximum height, it will start descending under the influence of gravity. The final speed when it hits the ground will depend on the initial speed and the distance it falls.
2. Stone thrown downwards: The stone is thrown vertically downward with the same initial speed. It will immediately start accelerating due to gravity and hit the ground after covering the distance.

Now, because both stones are subject to the same gravitational acceleration (which is constant), and both start with the same initial speed:

• The stone thrown upwards will first decelerate to zero speed at its highest point, and then accelerate towards the ground.
• The stone thrown downwards will immediately accelerate towards the ground.

However, in both cases, the final speed when they hit the ground will be the same because both stones are falling from the same height and have the same initial speed. The effect of gravity is the same for both stones, and the total change in speed (or final velocity) is determined by the initial speed and the distance traveled.

Therefore, the ratio of the speeds of the two stones when they hit the ground is 1:1.

Correct answer for the ssc chsl physics questions is Power of a lens

Explanation:
The diopter is the unit of power of a lens. The power of a lens is the reciprocal of its focal length (in meters), and it is expressed in diopters (D). The formula for the power of a lens is:

P = 1/f

Where:

• P is the power of the lens in diopters (D),
• f is the focal length of the lens in meters.

The unit of focal length is meters, so the unit of power is the reciprocal of meters, which is diopters (D), which is equal to the reciprocal of the focal length measured in metres (that is, 1/metres). It is thus a unit of reciprocal length.

Other Options:

1. Focal length of a lens: The focal length of a lens is measured in meters, not diopters.
2. Light intensity: Light intensity is typically measured in lumens or lux, not in diopters.
3. Sound intensity: Sound intensity is measured in decibels (dB), not diopters.

Thus, the diopter is the unit of the power of a lens.

Correct answer for the ssc chsl physics questions is Transverse

Explanation:
When a stone is thrown into the calm water of a pond, the waves produced on the surface of the water are transverse waves. In transverse waves, the particles of the medium (in this case, water) move perpendicular to the direction of the wave’s propagation.

When the stone hits the water, it displaces the water particles up and down (vertically), creating ripples that move outward. These ripples are examples of transverse waves because the water particles oscillate vertically while the wave travels horizontally across the surface.

Other Options:

1. Longitudinal waves: Longitudinal waves involve the movement of particles in the same direction as the wave propagation, such as sound waves in air. Water waves are not longitudinal, as the movement of water particles is up and down, not along the direction of wave travel.
2. Both longitudinal and transverse: While there are instances where both types of waves can exist, the typical surface waves in water (such as the ripples produced by a stone) are primarily transverse.
3. Waves are not produced: Waves are definitely produced when a stone is thrown into the water, so this option is incorrect.

Correct answer for the ssc chsl physics MCQ is Infra-red rays

Explanation:
In a filament-type light bulb (such as an incandescent bulb), most of the electric power consumed is converted into heat energy, which is primarily emitted as infrared rays. The filament inside the bulb gets heated by the electric current, and while it does emit some visible light, the majority of the energy is radiated as infrared radiation, which is felt as heat.

The visible light emitted is relatively small compared to the heat produced, which is why these bulbs are less energy-efficient compared to other lighting technologies like fluorescent or LED bulbs.

When electricity is passed through the filament of a light bulb, the filament gets hot due to the electrical resistance it offers to the current. As the temperature of the filament rises, it begins to emit radiation. The temperature of the filament in a typical incandescent bulb can reach over 2,000°C. At this high temperature, about 5% of the electrical energy is converted into visible light, while the remaining 95% is emitted as infrared radiation (heat).

Correct answer for the ssc chsl physics MCQ is Bad absorber and good reflector of heat

Explanation:
A white and smooth surface is a bad absorber and a good reflector of heat. This is because:

• White surfaces reflect most of the light and heat that falls on them, rather than absorbing it. The smoothness of the surface also enhances the reflection of heat.
• Dark-colored or rough surfaces tend to absorb more heat and radiate it, while light-colored and smooth surfaces reflect most of the incoming heat.

In the case of a white surface, it reflects most of the radiation (including heat) that hits it, rather than absorbing it, which is why it is a good reflector and a bad absorber of heat.

Correct answer for the ssc chsl physics MCQ is Both (1) and (2)

Explanation:
When a body is immersed in a liquid, two forces act on it:

1. Upthrust (Buoyant force): This is the force exerted by the liquid on the body in the upward direction. It is due to the displacement of the liquid by the body. According to Archimedes’ principle, the upthrust is equal to the weight of the liquid displaced by the body.
2. Weight: This is the force exerted by gravity on the body, pulling it downward. It is given by W=mg, where m is the mass of the body and g is the acceleration due to gravity.

Both forces act on the body when it is immersed in a liquid: the upthrust acting upward and the weight acting downward.

Correct answer for the ssc chsl physics MCQ is Rectifier

Explanation:
When p-type and n-type semiconductors are brought into contact, they form a p-n junction, which exhibits the properties of a rectifier. A rectifier allows current to flow in one direction only and blocks current in the opposite direction. This property is essential in converting alternating current (AC) to direct current (DC), and it is the fundamental operation of diodes, which are made from p-n junctions.

• The p-type semiconductor has an abundance of holes (positive charge carriers), while the n-type semiconductor has an abundance of electrons (negative charge carriers).
• When these two types of semiconductors are joined, they create a depletion region where electrons from the n-side and holes from the p-side recombine. This results in a barrier that only allows current to flow in one direction, making the p-n junction a rectifier.

Correct answer for the ssc chsl physics MCQ is Conductor

Explanation:
Ohm’s law states that the current (I) through a conductor between two points is directly proportional to the voltage (V) across the two points and inversely proportional to the resistance (R) of the conductor, expressed as:

V=I⋅R

This law is valid in the case of conductors because the relationship between voltage, current, and resistance remains linear in a conductor, where resistance is constant.

• Conductors (like metals) have a constant resistance, and current flows proportionally with voltage. Hence, Ohm’s law holds true for them under normal conditions (except in extreme cases like very high temperatures or when the material behaves non-linearly).

Other Options:

1. Semiconductor: Semiconductors do not follow Ohm’s law in the same way as conductors because their resistance varies with temperature and applied voltage. Their behavior is non-linear.
2. Superconductor: Superconductors have zero resistance when they are below their critical temperature, so they do not follow Ohm’s law because there is no resistance to obey the law.
3. Insulator: Insulators have very high resistance, and typically, very little current flows through them. While theoretically Ohm’s law could apply, in practice, insulators do not conduct current under normal conditions.

Correct answer for the ssc chsl physics MCQ is Coherent and monochromatic

Explanation:
A Laser (Light Amplification by Stimulated Emission of Radiation) produces a beam of light that is both coherent and monochromatic.

• Coherent means that the light waves are in phase with each other, both in frequency and amplitude. This results in a well-defined, stable beam of light.
• Monochromatic means the laser emits light at a single wavelength, or color, with very little spread in frequency.

This is what distinguishes a laser from other light sources, like ordinary light bulbs, which emit incoherent, polychromatic light.

Correct answer for the ssc chsl physics MCQ is The Centigrade (or Celsius) and Fahrenheit scales are related by the equation:

F = (9/5)C+32

To find the temperature at which both scales are the same, we can set F=C and solve for the temperature:

C = (9/5)C+32

Solving this:

C – (/9)5C =32

−(4/5)​C = 32

C = −(5×32)/4 = − 40

Therefore, the Centigrade and Fahrenheit temperatures are the same at –40°.

Other Options:

1. 32°: This is the freezing point of water in Fahrenheit, not where the two scales are the same.
2. 40°: This is not the point where the two scales are the same.
3. –273°: This is absolute zero in Celsius, but not the point where Centigrade and Fahrenheit scales are the same.

Correct answer for the ssc chsl physics MCQ is 24 cm

If v is the wave velocity and f is the frequency, wavelength (?) is given by:

λ = \(\displaystyle =\frac{v}{f}\)

So as per the question,

λ = 360/500 = 0.72

The path difference between two points is given by

\(\displaystyle \frac{\lambda }{{2\pi }}\times \phi =\frac{{0.72}}{{360}}\times 120=\)0.24 m = 24 cm

Correct answer for the ssc chsl physics MCQ is Incoming solar radiation

Explanation:
The term ‘insolation’ refers to the amount of incoming solar radiation that reaches the Earth’s surface from the Sun. It is a key factor in determining the Earth’s climate and weather patterns. The amount of solar radiation that reaches the Earth’s surface varies based on factors such as geographic location, time of year, and time of day. Insolation is influenced by the angle of the Sun’s rays, the duration of sunlight exposure, and cloud cover.

• Insolation is typically measured in terms of energy per unit area, often expressed in watts per square meter (W/m²). It represents the energy available for processes like photosynthesis, heating of the Earth’s surface, and driving weather systems.
• The highest insolation occurs at the equator because the Sun’s rays strike the Earth’s surface more directly there, while the polar regions receive much less direct sunlight, especially during the winter months.
• Factors affecting insolation:
  • Latitude: Areas near the equator receive more direct sunlight, leading to higher insolation.
  • Seasonal changes: During summer, the Earth’s tilt causes the Sun’s rays to be more direct, increasing insolation. In winter, the opposite happens.
  • Time of day: The angle of the Sun changes throughout the day, affecting the amount of solar radiation reaching the surface.
  • Atmospheric conditions: Clouds, air pollution, and other atmospheric conditions can scatter or absorb solar radiation, reducing the amount that reaches the Earth’s surface.

Correct answer for the ssc chsl physics MCQ is either equal to or greater than 1

A gear ratio greater than 1 means the output gear turns slower than the input gear. This reduction in speed results in an increase in torque at the output. Climbing a hill requires increased torque to overcome the resistance of gravity. Therefore, a gear ratio that provides more torque is needed. To get more torque, the gear ratio should be greater than 1. In some cases, a gear ratio of 1 might be sufficient for gentle slopes. While ascending a hill, the driver keeps the gear ratio either equal to or greater than 1. 

Correct answer for the ssc chsl physics MCQ is 16/25

As we know,

\(\displaystyle {{E}_{i}}=\frac{1}{2}m{{u}^{2}}\), \(\displaystyle {{E}_{f}}=\frac{1}{2}m{{v}^{2}}\)

Fraction of energy lost = \(\displaystyle \frac{{Ei-{{E}_{f}}}}{{Ei}}\)

\(\displaystyle =1-{{\left( {\frac{v}{u}} \right)}^{2}}=1-{{\left( {\frac{{m-4m}}{{m+4m}}} \right)}^{2}}\)

\(\displaystyle =1-\frac{9}{{25}}=\frac{{16}}{{25}}\)

Correct answer for the ssc chsl physics MCQ is Transverse waves on a string

Explanation:

• Transverse waves can be polarized because they oscillate in a direction perpendicular to the direction of the wave’s travel. This allows the oscillations to be confined to a single plane. In the case of waves on a string, the oscillations of the string (such as when you move one end of the string up and down) are perpendicular to the direction the wave is moving. Therefore, these waves can be polarized.
• Example of polarization: If a transverse wave on a string is traveling in a horizontal direction, the oscillations of the string itself will be vertical (or in any other direction perpendicular to travel). These oscillations can be restricted to a specific direction, making them suitable for polarization.

Other Options:

1. Sound waves in air:
   • Incorrect: Sound waves are longitudinal waves, meaning the particles of the medium (air, in this case) vibrate in the same direction as the wave travels. Since the oscillations occur along the direction of wave propagation, they cannot be polarized. Polarization occurs only in transverse waves, not in longitudinal waves.
   • Example: In sound waves, the air particles move back and forth in the direction of the wave, so there’s no possibility of restricting oscillations to a single plane, which is a key requirement for polarization.
2. Longitudinal waves on a string:
   • Incorrect: Just like sound waves in air, longitudinal waves on a string are not polarizable because the oscillations are in the same direction as the wave’s travel. In longitudinal waves, the string or medium moves back and forth in the direction of wave motion. Because the oscillations are along the same direction as wave propagation, there is no possibility of polarizing these waves.
   • Example: If you create a longitudinal wave on a string by compressing and releasing it, the motion of the string’s particles happens along the direction the wave travels, which makes polarization impossible.
3. Light waves:
   • Incorrect: While light waves are transverse and can be polarized, this option is a bit too broad, as the question asks specifically about the type of waves (like waves on a string). Light waves are electromagnetic waves and can indeed be polarized, but the more direct answer to the question, based on the choices provided, would be transverse waves on a string.
   • Example: Light waves, which are transverse waves, can oscillate in many directions perpendicular to the direction of propagation, and they can be polarized using filters that restrict the oscillation direction of the electric field component of the light.

Correct answer for the ssc chsl physics MCQ is \(\displaystyle Js\)

The Planck constant has dimensions of physical action; these are the same as those of angular momentum, i.e., energy multiplied by time, or momentum multiplied by distance. In SI units, the Planck constant is expressed in joule seconds (J·s) or (N·m·s).

Correct answer for the ssc chsl physics MCQ is R/4

Let the original length be L; area of cross-section be A; and the resistivity be ?.

So, R = ρ L/A

We get R∝L (as volume of the wire remains the same when it is recasted)

Now the wire is melted and recasted to half of its length i.e. L′=L/2

Also, Area will double

Thus new resistance of wire R′= R (l/2.2A)

R′= \(\displaystyle \frac{R}{4}\)

Thus, the new resistance is one-fourth of the original resistance.

Correct answer for the ssc chsl physics MCQ is Diffraction

Explanation:
The golden view of a sea shell is due to diffraction. When light interacts with the ridges or edges of an object like a sea shell, the light waves spread out and bend around the edges. This bending of light waves is called diffraction. In the case of the sea shell, this diffraction causes the light to interfere in such a way that a specific pattern or a “golden view” is seen as a result of how the light waves interact with the object’s surface.

Clarification Why the answer is not Polarization:

1. Polarization refers to the process in which light waves oscillate in a specific direction, usually due to the interaction with a filter or an optical material that allows only certain directions of vibration to pass through. It doesn’t explain the shimmering or color effects seen on a seashell surface.
2. Golden view of a seashell: The shimmering or golden appearance that we often see in seashells (and other similar objects) is generally due to diffraction or interference of light, not polarization. When light hits the surface of the shell, especially its intricate surface with ridges and grooves, the light waves bend and spread out (diffraction) or interact with each other (interference), leading to the colors and shimmering effects.
3. Polarization can occur in some scenarios (for example, with the use of polarized filters or surfaces that reflect light in a specific direction), but it is not the primary reason for the golden view of a seashell.

Correct answer for the ssc chsl physics MCQ is constant

When an object covers distance which is directly proportional to the square of the time, its acceleration is constant. This is seen in the cases of falling objects. This connection between time and distance was first observed by Galileo.

Correct answer for the ssc chsl physics MCQ is Reflection, refraction, and dispersion of light in water droplets

Explanation:
A rainbow is formed due to a combination of the following processes:

1. Refraction: When sunlight enters a water droplet, it bends or refracts because light travels at different speeds in different mediums (from air to water). This bending occurs because of the change in the speed of light as it passes from one medium to another.
2. Reflection: After refraction, the light reaches the inner surface of the water droplet, where it is reflected off the back of the droplet. This reflection is critical because it allows the light to travel back through the droplet and exit on the other side.
3. Dispersion: As the light exits the droplet, it undergoes dispersion, which is the separation of light into its constituent colors. This occurs because different wavelengths (colors) of light travel at different speeds, causing them to spread apart. Shorter wavelengths (blue and violet) bend more than longer wavelengths (red and orange), creating a spectrum of colors.

These combined effects—refraction, reflection, and dispersion—are what create the rainbow.

Correct answer for the ssc chsl physics MCQ is Low atmospheric pressure

Explanation:
The boiling point of water decreases at higher altitudes because of the lower atmospheric pressure. At sea level, the atmospheric pressure is higher, and water boils at 100°C. However, as you ascend to higher altitudes, the atmospheric pressure decreases, which causes the boiling point of water to decrease as well.

• Boiling point is the temperature at which the vapor pressure of the liquid equals the atmospheric pressure. When the atmospheric pressure is lower, it takes less heat for the liquid’s vapor pressure to match the external pressure, so the liquid will boil at a lower temperature.

At high altitudes, the reduced air pressure means water boils at temperatures lower than 100°C. For example, at 2,500 meters (about 8,200 feet) above sea level, the boiling point of water is about 92°C.

Other Options:

1. Low temperature: While lower temperatures might affect other physical properties of substances, it is the lower atmospheric pressure that primarily causes the boiling point to decrease at higher altitudes.
2. High temperature: High temperature would increase the boiling point, but the decrease in boiling point at higher altitudes is due to lower, not higher, temperatures.
3. High atmospheric pressure: High atmospheric pressure would cause the boiling point to increase, not decrease. This is why pressure cookers can cook food faster – they increase the atmospheric pressure inside the cooker.

Thus, the boiling point of water decreases at higher altitudes due to low atmospheric pressure.

Correct answer for the ssc chsl physics MCQ is

\(\displaystyle {{n}_{2}}={{n}_{1}}\left( {\frac{{{{M}_{1}}}}{{{{M}_{2}}}}} \right)\left( {\frac{{{{L}_{1}}}}{{{{L}_{2}}}}} \right){{\left( {\frac{{{{T}_{1}}}}{{{{T}_{2}}}}} \right)}^{{-2}}}\)

\(\displaystyle {{n}_{2}}=1\left( {\frac{{{{{10}}^{3}}}}{{10}}} \right)\left( {\frac{{{{{10}}^{2}}}}{{10}}} \right){{\left( {\frac{1}{{0.1}}} \right)}^{{-2}}}=10\)

Thus if the new unit of force is

10 X = 1 N or X = 0.1