[solved] Physics questions with answers – CDS Exam Last 15 years Solved Questions

CDS Exam Physics questions with answers (including explanations) of the Last 15 years | CDS OTA Exam – Physics questions with solution | Latest CDS Exam Physics questions with answers | Multiple Choice Questions (MCQs) of Physics

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CDS Exam Solved Physics questions

Physics Questions with Explanation
Chemistry Questions with Explanation
Biology Questions with Explanation
History Questions with Explanation
Geography Questions with Explanation
Polity Questions with Explanation
Economics Questions with Explanation
General Knowledge Questions with Explanation
Miscellaneous Questions with Explanation

1. Which one of the following Indian scientists was elected as a fellow of the Royal Society of London for his contribution in the field of plant Physiology and Physics?

(a) Ashutosh Mukherjee
(b) Jagdish Chandra Bose
(c) Prafulla Chandra Ray
(d) P C Mahalandodis

Answer – (b) Jagdish Chandra Bose
Jagdish Chandra Bose was elected as a fellow of the Royal Society of London for his contribution to the field of plant Physiology and Physics.

2. Assertion (A): Steam is more harmful to the human body than boiling water in case of a burn.
Reason (R): Boiling water contains more heat than steam.

(a) Both A and R are true and R is the correct explanation of A
(b) Both A and R are true, but R is not the correct explanation of A
(c) A is true, but R is false
(d) A is false, but R is true

Answer – (c) A is true, but R is false
Steam burns are more serious than burns from boiling water even though both are at 100℃ because when steam condenses it gives up very high heat energy i.e. additional 22.6 × 105 joule of heat (the latent heat of vapourization) compared to boiling water.

3. Why is it difficult to see through the fog?

(a) Rays of light suffer total internal reflection from the fog droplets
(b) Rays of light are scattered by the fog droplets
(c) Fog droplets absorb light
(d) The refractive index of fog is extremely high

Answer – (b) Rays of light are scattered by the fog droplets
The rays of light are scattered by the fog droplets due to which it becomes difficult to see through the fog.

4. The density of water varies with temperature which helps the aquatic animals to live in cold water. At what temperature is the density of water maximum?

(a) 1℃
(b) 2℃
(c) 3℃
(d) 4℃

Answer – (d) 4℃
The density of water is maximum at 4℃

5. Who gave the first evidence of the big-bang theory?

(a) Edwin Hubble
(b) Albert Einstein
(c) S Chandrasekhar
(d) Stephen Hawking

Answer – (a) Edwin Hubble
Edwin Hubble gave the first evidence of the big-bang theory.

6. A ray of light is incident on a plane mirror at an angle 30° with the normal at the point of incidence. The ray will be deviated from its incidence direction by what angle?

(a) 30°
(b) 60°
(c) 120°
(d) None of these

Answer – (b) 60°
The given situation can be shown as

By the law of reflection, angle of incidence i is equal to the angle of reflection r
Total deviation of ray = 30° + 30° = 60°

7. What would be the best choice for window material to keep the outside heat away?

(a) Single-pane glass
(b) Double-pane glass without a gap in between
(c) Double-pane glass with water filled in between
(d) Double-pane glass with air in between

Answer – (d) Double-pane glass with air in between
To keep the outside heat away, windows of double-pane glass with air in between is the best choice because air is the bad conductor of heat.

8. A bar is a unit of which one of the following?

(a) Force
(b) Energy
(c) Pressure
(d) Frequency

Answer – (c) Pressure
1 Bar = 105 Pa. Both bar and Pa are the units of pressure.

9. On which one of the following conservative laws, does a rocket work?

(a) Mass
(b) Energy
(c) Linear momentum
(d) Angular momentum

Answer – (c) Linear momentum
Rocket works on the principle of conservation of linear momentum.

10. Assertion (A): In a pressure cooker food is cooked above boiling point.
Reason (R): Boiling point of water increases as the pressure increases.

(a) Both A and R are true and R is the correct explanation of A
(b) Both A and R are true, but R is not the correct explanation of A
(c) A is true, but R is false
(d) A is false, but R is true

Answer – (a) Both A and R are true and R is the correct explanation of A
In a pressure cooker while cooking pressure increases due to which boiling point of water also increases as P ∝ T.

11. The phenomenon of mirage occurs due to which one of the following?

(a) Polarisation of light
(b) Dispersion of light
(c) Diffraction of light
(d) Total internal reflection of light

Answer – (d) Total internal reflection of light
Total internal reflection is responsible for mirage formation in deserts.

12. Which one of the following common devices works on the basis of the principle of mutual induction?

(a) Tubelight
(b) Transformer
(c) Photodiode
(d) LED

Answer – (b) Transformer
Transformer is based on the principle of mutual induction.

13. Television signal cannot be received generally beyond a particular distance due to

(a) the curvature of the Earth
(b) weakness of antenna
(c) weakness of signal
(d) absorption of signal in the air

Answer – (a) the curvature of the Earth
The curvature of the earth does not allow the television signals to be received beyond a particular distance.

14. If a small raindrop falls through air

(a) its velocity goes on increasing
(b) its velocity goes on decreasing
(c) its velocity goes on increasing for some time and then becomes constant
(d) it falls with constant speed for some time and then its velocity increases

Answer – (c) its velocity goes on increasing for some time and then becomes constant
The velocity of the raindrops increases until it reaches the terminal velocity.

15. Consider the following statements
X-rays

1. can pass through aluminum.
2. can be deflected by the magnetic field.
3. move with a velocity less than the velocity of ultraviolet rays In a vacuum.
Which of the statements given above is/are correct?

(a) 1, 2 and 3
(b) Only 1
(c) 2 and 3
(d) 1 and 2

Answer – (b) Only 1
X-rays cannot be deflected by a magnetic field as they consist of no charge.
X-rays and UV rays are electromagnetic waves, so they move with the same velocity in a vacuum i.e. 3 × 108 m/s.

16. Which one of the following is the permissible level of noise in a silent zone in the daytime?

(a) 50 dB
(b) 60 dB
(c) 65 dB
(d) 75 dB

Answer – (a) 50 dB
The permissible level is 50 dB.

17. By which one of the following, an old written material which cannot be read easily, can be read

(a) γ-rays
(b) X-rays
(c) IR-rays
(d) Radiofrequency waves

Answer – (c) IR-rays
Infrared rays help in reading old written material.

18. Earthquake (shock) waves are

(a) infrasonic waves
(b) ultrasonic waves
(c) seismic
(d) infrared waves

Answer – (c) seismic
An Earthquake is the result of a sudden release of energy in the Earth’s crust that creates seismic waves.

19. A laser is a device to produce ___

(a) a beam of white light
(b) coherent light
(c) microwaves
(d) X-rays

Answer – (b) coherent light
A laser is a device that emits coherent light through a process called stimulated emission.

20. A perfect black body has the unique characteristic feature as

(a) a good absorber only
(b) a good radiator only
(c) a good absorber and a good radiator
(d) neither a radiator nor an absorber

Answer – (c) a good absorber and a good radiator
A perfect black body emits and absorbs all colors of light. A good absorber is a good emitter.

21. Fat can be separated from milk in a cream separation because of ___

(a) cohesive force
(b) gravitational force
(c) centrifugal force
(d) centripetal force

Answer – (c) centrifugal force
Centrifugal force separates fat from milk.

22. Which one of the following is not the result of surface tension?

(a) Vapor formation above the liquid surface
(b) The convex shape of the liquid meniscus
(c) Liquid rising in a capillary
(d) The spherical shape of mercury fell on the floor

Answer – (a) Vapor formation above the liquid surface
Vapor formation above the liquid surface

23. The hair of a shaving brush cling together when the brush is removed from water due to __

(a) viscosity
(b) surface tension
(c) friction
(d) elasticity

Answer – (b) surface tension
When the brush is taken out, the water film is formed between the hairs and they contract due to surface tension.

24. Consider the following statements

1. Clear sky appears blue due to poor scattering of the blue wavelength of visible light.
2. Red part of light shows more scattering than blue light in the atmosphere.
3. In the absence of atmosphere, there would be no scattering of light and the sky will look black.
Which of the statements given above is/are correct?

(a) Only 1
(b) 1 and 2
(c) Only 3
(d) All of these

Answer – (c) Only 3
The appearance of the blue color of the sky is due to the scattering of light which is not possible in absence of atmosphere.

25. The most familiar form of radiant energy in sunlight that causes tanning and sunburning of human skin, is called

(a) ultraviolet radiation
(b) visible radiation
(c) infrared radiation
(d) microwave radiation

Answer – (a) ultraviolet radiation
The tanning and sun burning of human skin are due to the harmful ultraviolet radiation from the sun.

26. A boy throws four stones of the same shape, size, and weight with the equal speed at different initial angles with the horizontal line. If the angles are 15°, 30°, 45°, and 60°, at which angle the stone will cover the maximum horizontally?

(a) 15°
(b) 30°
(c) 45°
(d) 60°

Answer – (c) 45°


27. Which one of the following statements is true?

(a) Temperatures differing 25° on the Fahrenheit (F) scale must differ by 45° on the Celsius (C) scale
(b) 0℉ corresponds to – 32℃
(c) Temperatures that differ by 10° on the Celsius scale must differ by 18° on the Fahrenheit scale
(d) Water at 90℃ is warmer than water at 202℉

Answer – (c) Temperatures that differ by 10° on the Celsius scale must differ by 18° on the Fahrenheit scale
By the relation in different temperature scales

We can calculate that temperatures that differ by 10° on the Celsius scale must differ by 18° on the Fahrenheit scale.

28. A diffraction pattern is obtained using a beam of red light. Which one among the following will be the outcome, if the red light is replaced by blue light?

(a) Bands disappear
(b) The diffraction pattern becomes broader and further apart
(c) The diffraction pattern becomes narrower and crowded together
(d) No change

Answer – (c) The diffraction pattern becomes narrower and crowded together
The diffraction pattern becomes narrower and crowded together.

29. Raw mangoes shrivel when pickled in brine. The phenomenon is associated with ___

(a) osmosis
(b) reverse osmosis
(c) increase of surface tension of the fluid
(d) decrease of surface tension of the fluid

Answer – (a) osmosis
Raw mangoes shrivel when pickled in brine due to osmosis i.e. flow of water from higher concentration to lower concentration through a semi-permeable membrane.

30. The apparent weight of a steel sphere immersed in various liquids is measured using a spring balance. The greatest reading is obtained for the liquid

(a) having the smallest density
(b) having the largest density
(c) in which the sphere was submerged deepest
(d) having the greatest volume

Answer – (a) having the smallest density
When a body is immersed in a liquid, then the apparent weight of the body depends upon the densities of the liquids and volume of the portion of the solid immersed in liquid. So, the apparent weight of a steel sphere will be greatest for the liquid with the smallest density.

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