Science & Technology › Physics – UPSC Prelims PYQs
102 questions · 1995–2021 · answers as per the UPSC key · page 2 of 3
Two wires have their lengths, diameters and resistivities, all in the ratio of 1 : 2. If the resistance of the thinner wire is 10 ohms, the resistance of the thicker wire is
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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): The light coming from the stick undergoes scattering from water molecules giving the stick a short and bent appearance.
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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.
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Assertion (A): The boiling point of water decreases as the altitude increases.
Reason (R): The atmospheric pressure increases with altitude.
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When light waves pass from air to glass, the variables affected are
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When water is heated from 0 °C to 10 °C, its volume
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Match List I with List II
and select the correct answer using the codes given below the Lists:
List I (Characteristic) I. Zero mass II. Fractional charge III. Fractional spin IV. Integral spin
List II (Particle) A) Positron B) Neutrino C) Quark D) Phonon
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The mass of a body on Earth is 100 kg (acceleration due to gravity, gₑ = 10 m/s²). If acceleration due to gravity on the Moon = gₑ/6, then the mass of the body on the moon is
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Consider the following statements: A simple pendulum is set into oscillation. Then I. The acceleration is zero when the bob passes through the mean position. II. In each cycle the bob attains a given velocity twice. III. Both acceleration and velocity of the bob are zero when it reaches its extreme position during its oscillation. IV. The amplitude of oscillation of the simple pendulum decreases with time.
Which of these statements are correct?
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Which one of the following does a TV remote control unit use to operate a TV set?
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A noise level of 100 decibels would correspond to
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Fluorescent tubes are fitted with a choke. The choke coils
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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
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Assertion (A): A man standing on a completely frictionless surface can propel himself by whistling.
Reason (R): If no external force acts on a system, its momentum cannot change.
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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.
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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 back into a rarer medium.
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Assertion (A): Large cold storage plants use ammonia as refrigerant while domestic refrigerators use chlorofluorocarbons.
Reason (R): Ammonia can be liquified at ambient temperatures at low pressures.
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Consider the following
statement: An ordinary light bulb has a rather short life because the I. Filament wire is not uniform. II. Bulb cannot be evacuated completely. III. Wires supporting the filament melt at high temperatures.
Which of the above statements are correct?
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Match List I (Quantity) with List II (Units) and select the correct answer using the codes given below the Lists:
List I I. High speed II. Wavelength III. Pressure IV. Energy
List II A) Mach B) Angstrom C) Pascal D) Joule
Codes:
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Consider the following statements: I. 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. II. 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?
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Endoscopy, a technique used to explore the stomach or other inner parts of the body is based on the phenomenon of
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Strips of two metals A and B are firmly joined together as shown in the figure. On heating, A expands more than B does. If this joined strip is heated, then it will appear as:
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Low temperatures (Cryogenics) find application in
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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
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A fuse is used in main electric supply as a safety device.
Which one of the following statements about the fuse is correct?
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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 3 seconds?
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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.
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The tendency of a liquid drop to contract and occupy minimum area is due to
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Which one of the following is a vector quantity?
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Which one of the following is a valid conclusion?
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The working principle of a washing machine is
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A smooth inclined plane is inclined at an angle θ with the horizontal as shown in the figure. A body starts from rest and slides down the inclined surface. The time taken by the body to reach the bottom is
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A girl is swinging on a swing in sitting position. When the same girl stands up, the period of swing will
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I. ‘A’ stood first in the race. II. ‘C’ led all the way.
III. ‘D’ ran faster than others in the later part of the race. Of these statements
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When an air bubble at the bottom of a lake rises to the top, it will
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When a mirror is rotated by an angle of θ, the reflected ray will rotate by
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A truck, a car and a motor cycle have equal kinetic energies. If equal stopping ...
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A liquid is flowing in a streamlined manner through a cylindrical pipe. Along a section containing the axis of the pipe, the flow profile will be
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The variation of displacement (d) with time (t) in the case of a particle falling freely under gravity from rest is correctly represented by which of the following graphs?
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Total internal reflection can take place when light travels from
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Assertion (A): Transformer is useful for stepping up or stepping down voltages.
Reason (R): Transformer is a device used in D.C. circuits. In the context of the above two statements, which one of the following is correct?
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Domestic electrical wiring is basically a
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A simple machine helps a person doing
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The alpha particle carries two positive charges. Its mass is very nearly equal to that of
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A parachutist jumps from a height of 5000 metres. The relationship between his falling speed ‘v’ and the distance fallen through ‘d’ is best represented as (four graphs labelled a, b, c, d).
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Which one of the following can be used to confirm whether drinking water contains a gamma-emitting isotope or not?
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The normal temperature of human body on the Kelvin scale is
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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
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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. In the context of the above two statements, which one of the following is correct?
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Optical fibre works on the principle of