UPSC IAS Prelims Base – Physics

Which one of the following is a vector quantity?

Who among the following anticipated Newton by declaring that all things gravitate to the earth?

Who among the following anticipated Newton by declaring that all things gravitate to the earth?

A simple machine helps a person in doing:

A simple machine helps a person in doing:

The tendency of a liquid drop to contract and occupy minimum area is due to :

Which one of the following is a vector quantity?

A girl is swingingon a swing in sitting position. When the girl stands up, the period of swing will :

A girl is swingingon a swing in sitting position. When the girl stands up, the period of swing will :

The working principle of a washing machine is :

A ball is dropped from the top of a high building with a constant acceleration of 9.8 m/s². What will be its velocity after 2 seconds?

A ball is dropped from the top of a high building with a constant acceleration of 9.8 m/s². What will be its velocity after 2 seconds?

A hunter aims his gun at a point between the eyebrows of a monkey sitting on a branch of a tree. Just as he fires, the monkey jumps down. The bullet will :

For which one of the following is capillarity not the reason?

Consider the following features of newer models of motor cars: 

1. Radial tyres
2. Streamlined body
3. Multipoint fuel injection
4. Catalytic converter with exhaust

Which of these features make the new models of motor cars more fuel efficient?

Assertion (A): A man standingon a completely frictionless surface can propel himself by whistling.
Reason (R) : If no external force acts on a system, its momentum cannot change.

The mass of a body on earth is 100 kg (acceleration due to gravity, g = 10m/s². If acceleration due to gravity on the moon is g.16, then the mass of the body on the moon is : 

Consider the following statements
A simple pendulum is set into oscillation.
Then:

1. the acceleration is zero when the bob passes through the mean position.
2. in each cycle the bob attains a given velocity
3. both acceleration and velocity of the bob are zero when it reaches its extreme position during the
4. the amplitude of oscillation of the simple pendulum decreases with time.

Which of these statements are correct?

Consider the following statements
A simple pendulum is set into oscillation.
Then:

1. the acceleration is zero when the bob passes through the mean position.
2. in each cycle the bob attains a given velocity
3. both acceleration and velocity of the bob are zero when it reaches its extreme position during the
4. the amplitude of oscillation of the simple pendulum decreases with time.

Which of these statements are correct?

Assertion (A) : With the increase of temperature, the viscosity of glycerine increases.
Reason (R) : Rise of temperature increases kinetic energy of molecules.

Assertion (A): An iron ball floats on mercury but gets immersed in water.
Reason (R): The specific gravity of iron is more than  that of mercury.

A solid cube gets completely immersed in water when a 0.2 kg mass is placed on it. If the mass is removed, the cube is 2 cm above the water level. What is the length of each side of the cube?

Assertion (A) : The weight of a body decreases with the increase of altitude on earth.
Reason (R) : The earth is not a perfect sphere.

Consider the following statements:
A 4-wheel vehicle moving in a sharp circular path at high speed will :

1. overturn about its outer wheels
2. overturn about its inner wheels
3. skid outwards
4. skid inwards

Which of these statements are correct?

An oil tanker partially filled with oil moves forward  on a level road with uniform acceleration. The free  surface of oil then:

If the radius of the earth were to shrink by one percent, its mass remaining the same, the value of g on  the earth’s surface would:

A car is running on a road at a uniform speed of 60  km/h. The net resultant force on the car is :

A spherical body moves with a uniform angular  velocity (w) around a circular path of radius (r). Which one of the following statements is correct?

A weightless rubber balloon is filled with 200 cc of water. Its weight in water is equal to :

Which one of the following is the correct sequence of  the given substances in the decreasing order of their  densities?

What is the approximate mean velocity with which  the earth moves round the sun in its orbit?

Four wires of same material and of dimensions as under are stretched by a load of same magnitude separately. Which one of them will be elongated maximum?

Three identical vessels A, Band C are filled with water, mercury and kerosene respectively up to an equal height. The three vessels are provided with identical taps at the bottom of the vessels. If the three taps are opened simultaneously, then which vessel is emptied first

Consider the following statements :
If there were no phenomenon of capillarity

1. it would be difficult to use a kerosene lamp
2. one would not be able to use a straw to consume a soft drink
3. the blotting paper would fail to function
4. the big trees that we see around would not have grown on the Earth

Which of the statements given above are correct?

Ball bearings are used in bicycles, cars, etc., because

Clouds float in the atmosphere because of their low ?

Low temperatures (cryogenics) find application in

Low temperatures (cryogenics) find application in

Assertion (A): A piece of copper and a piece of glass are heated to the same temperature. When touched, thereafter, the copper piece appears hotter than the glass piece.
Reason (R) : The density of copper is more than that of glass.

Assertion (A) : The boiling point of water decreases as the altitude increases.
Reason (R) : The atmospheric pressure increases with altitude.

When water is heated from 0°C to 10⁰C. Its volume:

A hollow sphere of radius R, a hollow cube of side R and a thin circular plate of radius R., made up of the same material, are all heated to 20°C above room temperature. When left to cool in the room, which of them will reach the room temperature first?

Consider the following statements:

1. Steam at 100°C and boiling water at 100°C contain same amount of heat.
2. Latent heat of fusion of ice is equal to the latent heat of vaporization of water.
3. In an air-conditioner, heat is extracted from the room air at the evaporator coils and is rejected out at the condenser coils.

Which of these statements is/are correct?

Cloudy nights are warmer compared to clear cloudless nights, because clouds:

The surface of a lake is frozen in severe winter, but the water at its bottom is still liquid. What is the reason ?

When the same note is played on a sitar and a flute, the sound produced can be distinguished from each other because of the difference in:

Assertion (A): A diamond sparkles more than a glass imitation cut to the same shape.
Reason (R) : The refractive index of diamond is less than that of glass.

Optical fibre works on the principle of :

Suppose a rocketship is receding from the earth at a speed of 2/10 th the velocity of light. A light in the rocketship appears blue to the passengers on the ship. What colour would it appear to an observer on the earth

An air bubble in water will act like a :

When a mirror is rotated by an angle ‘a’, the reflected  ray will rotate by :

Total internal reflection can take place when light travels from:

Total internal reflection can take place when light travels from:

Consider the following statements:

1. If a person looks at a coin which is in a bucket of water, the coin will appear to be closer than it really is.
2. If a person under water looks at a coin above the water surface, the coin will appear to be at a higher level than it really is

Which of the above statements is/are correct?

A noise level of 100 decibel would correspond to:

Assertion (A): In a motion picture, usually 24 frames are projected every second over the whole length of the film.
Reason (R) : An image formed on the retina of eye  persists for about 0.1 s after the removal of stimulus.

Assertion (A) :Small glass beads fixed on traffic signals glow brightly when light falls upon them.
Reason (R) : Light is totally reflected when the angle of incidence exceeds a certain critical value and light travelling in a denser medium is reflected from a rarer medium.

When a CD (compact disc used in audio and video systems) is seen in sunlight, rainbow like colours are seen. This can be explained on the basis of the phenomenon of :

Assertion (A): A stick is dipped in water in a slanting position. If observed sideways, the stick appears short and bent at the surface of water.
Reason (R): A light coming from the stick undergoes  scattering from water molecules giving the stick a  short and bent appearance.

When light waves pass from air to glass, the variables affected are:

Consider the following statements:

1. Light of longer wavelength are scattered much more than the light of shorter wavelength.
2. The speed of visible light in water is 0.95 times the speed in vacuum.
3. Radio waves are produced by rapidly oscillating electrical currents.
4. Todetect the overspeeding vehicles, police use the Doppler effect of reflected short radio waves.

Which of these statements are correct?

Consider the following natural phenomena: 

1. Terrestrial heating
2. Reflection of light
3. Refraction of light
4. Diffraction of light

Due to which of these phenomena is a mirage formed?

Diffusion of light in the atmosphere takes place due to :

Which one of the following statements is not correct?

In which one among the following is the speed of sound maximum?

Consider the following statements:

1. If magenta and yellow coloured circles intersect, the intersected area will have red colour.
2. If cyan and magenta coloured circles intersect, the intersected area will have blue colour.

Which of the statements given above Ware correct?

Consider the following statements 

1. A flute of smaller length produces waves of lower
2. Sound travels in rocks in the form of longitudinal elastic waves only.

Which of the statements given above is/are correct?

Assertion (A): A jet aircraft moving at Mach Number equal to 1 travels faster at an altitude of 15 km than while moving at Mach Number equal to 1 near the sea level.
Reason (R) : The velocity of sound depends on the temperature of the surrounding medium.

Assertion (A): Radio waves bend in a magnetic field.
Reason (R): Radio waves are electromagnetic in nature

Which one of the following types of waves are used in a night vision apparatus ?

Consider the following phenomena: 

1. Size of the sun at dusk.
2. Colour of the sun at dawn
3. Moon being visible at dawn
4. Twinkle of stars in the sky
5. Polestar being visible in the sky

Which of the above are optical illusions?

Consider the following phenomena: 

1. Size of the sun at dusk.
2. Colour of the sun at dawn
3. Moon being visible at dawn
4. Twinkle of stars in the sky
5. Polestar being visible in the sky

Which of the above are optical illusions?

Rainbow is produced when sunlight falls on drops of rain. Which of the following physical phenomena are responsible for this?

1. Dispersion
2. Refraction
3.  Internal reflection

Select the coned answer using the codes below

During a thunderstorm, the thunder in the skies is produced by the

1. meeting of cumulonimbus clouds in the sky
2. lightning that separates the nimbus clouds
3. violent upward movement of air and water particles

Select the correct answer using the codes given below.

Assertion (A): Transformer is useful for stepping up or stepping down voltages.
Reason (R): Transformer is a device used in D.C. circuits.

Domestic electrical wiring is basically a :         

Which one of the following is paramagnetic in nature?

A fuse is used in mains electric supply as a safety device. Which one of the following statements about the fuse is correct?

Assertion (A) : The temperature of a metal wire rises when an electric current is passed through it.
Reason (R) : Collision of metal atoms with each other releases heat energy.

Consider the following statements
An ordinary light bulb has a rather short life because the:

1. filament wire is not uniform.
2. bulb cannot be evacuated completely.
3. wires supporting the filament melt at high

Which of the above statements are correct?

Consider the following statements regarding a motor car battery: 

1. The voltage is usually 12 V.
2. Electrolyte used is hydrochloric acid.
3. Electrodes are lead and copper.
4. Capacity is expressed in ampere-hour.

Which of the above statements are correct?

Fluorescent tubes are fitted with a choke. The choke coil :

Two wires have their lengths, diameters and resistivities all in the ratio of 1 : 2. If the resistance of the thinner wire is 10 ohm, the resistance of the thicker wire is

Assertion (A) : In our houses, the current in A.C. electricity line changes direction 60 times per second.
Reason (R) : The frequency of alternating voltage supplied is 50 Hz.

What is the order of magnitude of electric resistance of the human body (dry) ?

Which one of the following is printed on a commonly used fluorescent tube light?

Graphene is frequently in news recently. What is its importance?

1. It is a two-dimensional material and has good electrical conductivity.
2. It is one of the thinnest but strongest materials tested so far.
3. It is entirely made of silicon and has high optical
4. It can be used as ‘conducting electrodes’ required for touch screens, LCDs and organic LEDs.

Which of the statements given above are correct?

Electrically charged particles from space travelling at speeds of several hundred km/sec can severely harm living beings if they reach the surface of the Earth. What prevents them from reaching the surface of the Earth?

The known forces of nature can be divided into four classes, viz., gravity, electromagnetism, weak nuclear force and strong nuclear force. With reference to them, which one of the following statements is not correct?

The technique used to transmit audio signals in television broadcasts is :

Consider the following statements:
At the present level of technology available in India, solar energy can be conveniently used to :

1. Supply hot water to residential buildings
2. Supply water for minor irrigation projects.
3. Provide street lighting.
4. Electrify a cluster of villages and small towns.

One astronomical unit is the average distance between:

For reproducing sound, a CD (Compact Disc) audioplayer uses a :

Which one of the following does a TV remote control unit use to operate a TV set?

Consider the following statements:
In a nuclear reactor, self-sustained chain reaction is possible, because:

1. more neutrons are released in each of the fission
2. the neutrons immediately take part in the fission
3. the fast neutrons are slowed down by graphite.
4. every neutron released in the fission reaction initiates further fission.

Which of these statements are correct?

Consider the following statements 

1. A geo-stationary satellite is at an approximate height of 10,000 km.
2. FM transmission of music is of very good quality because the atmospheric or man made noises which are generally frequency variations can do little harm.

Which of the statements give above is/are correct?

What does the term Dolby B or Dolby C printed on tape recorders and other sound systems refer to:

Which of the following types is used by computed tomography employed for visualisation of the internal structure of human body?

The efforts to detect the existence of Higgs boson particle have become frequent news in the recent past. What is/are the importance / importances of discovering this particle?

1. It will enable us to understand as to why elementary particles have mass.
2. It will enable us in the near future to develop the technologyof transferring matter from one point to another without traversing the physical space between them.
3. It will enable us to create better fuels for nuclear

Select the correct answer using the codes given below.

With reference to ‘fuel cells’ in which hydrogen-rich fuel and oxygen are used to generate electricity. Consider the following statements : 

1. If pure hydrogen is used as a fuel, the fuel cell emits heat and water as by-products.
2. Fuel cells can be used for powering buildings and not for small devices like laptop computers.
3. Fuel cells produce electricity in the form of Alternating Current (AC).

Which of the statements given above is / are correct?

Cryogenic engines find applications in :

Consider the following statements
A person in a spaceship located half way between the earth and the sun will notice that the :

1. sky is jet black.
2. stars do not twinkle.
3. temperature outside the spaceship is much higher than that on the surface of the earth.

The tail of a comet is directed away from the sun because:

A ‘black hoke’ is a body in space which does not allow any radiation to come out. This property is due to its :

Consider the following statements in respect of India advanced satellite INSAT-4A: 

1. INSAT-4A was launched in December, 2005 from New Mexico.
2. The European Commercial Launch Service Provider Arianespace was associated with the launch of !NSA T-4A.
3. Tata-Sky; a digital cable service provider; is associated with DTH television broadcasting service from INSA T 4A.

Which of the statements given above are correct?

In which of the following activities are Indian Remote Sensing (IRS) satellites used ?

1. Assessment of crop productivity
2. Locating grundwater resourses
3. Mineral exploration
4. Telecommunications
5. Traffic studies

Select the correct answer using the codes given below.