Physics MCQs
Physics Objective (Multiple Choice) General Knowledge & General Science Questions & Answers for SSC-CGL, UPPSC, NDA, CDS and all one day examinations of India.
1. Which among the following is true regarding Sound Waves?
[A] They are longitudinal waves and material medium is not required for their propagation
[B] They are transverse waves and material medium is required for their propagation
[C] They are longitudinal waves and material medium is required for their propagation
[D] They are transverse waves and material medium is not required for their propagation
Show Answer
Correct Answer: C [They are longitudinal waves and material medium is required for their propagation]
Notes:
The sound waves are longitudinal waves and material medium is not required for their propagation. The sound waves can travel through solid, liquid and gas.
2. When light from some sources enters to the earth’s atmosphere, it gets scattered. Which among the following is a reason behind scattering?
[A] Various wavelengths of light
[B] dust, smoke and gas molecules
[C] atmospheric pressure
[D] None of the above
Show Answer
Correct Answer: B [dust, smoke and gas molecules]
Notes:
Scattering of light is the phenomenon in which light rays get deviated from its straight path on striking an obstacle.The scattering of light can be of many reason. Some of them are dust, smoke and gas molecules.
3. We can hear a whooshing sound when we hold a spiral conch shell near our ears. What is the most likely reason behind this?
[A] The sound we hear is echoing of our blood rushing through the blood vessels of our ear
[B] The sound is generated by air flowing through the shell – in and out
[C] The ambient noise around us resonates inside the shell
[D] None of the reasons mentioned in statements A, B or C is correct
Show Answer
Correct Answer: C [ The ambient noise around us resonates inside the shell]
Notes:
The most likely explanation for the wave-like noise is ambient noise from around us. The seashell that we hold just slightly above our ear captures this noise, which resonates inside the shell.
4. The spray bottles used as window or household cleaner or perfume spray works on:
[A] Capillary action
[B] Bernoulli’s Principle
[C] Pascal’s Law
[D] Stoke’s Law
Show Answer
Correct Answer: B [ Bernoulli’s Principle]
Notes:
When we press the top of bottle the pressure at top of the bottle decreases and hence, the velocity of liquid flow increases. Bernoulli’s Principle states that an increase in the speed of a fluid produces a decrease in pressure and that a decrease in the speed of a fluid produces an increase in pressure. The principle states that the total energy of a moving fluid remains constant at all times.
5. Who among the following is credited for the Corpuscular theory of light?
[A] Isaac Newton
[B] Christiaan Hyugens
[C] Albert Einstein
[D] James Clerk Maxwell
Show Answer
Correct Answer: A [Isaac Newton]
Notes:
The Corpuscular theory of light was given by Isaac Newton. It was replaced by Huygens’ wave theory when it failed to adequately explain the diffraction, interference and polarization of light. The Huygens’ wave theory was replaced by Planck’s quantum theory and finally de-Broglie’s Dual-Theory of light replaced all previous ones.
6. What is the slope of the velocity-time graph when an object moves with constant negative acceleration, having positive initial velocity?
[A] 90°
[B] more than 90°
[C] less than 90°
[D] 0°
Show Answer
Correct Answer: B [more than 90°]
Notes:
When an object moves with constant negative acceleration, having positive initial velocity, the velocity-time graph is a straight line having slope more than 90°. When an object moves with constant positive acceleration, having positive initial velocity, the velocity-time graph is a straight line having slope less than 90°.
7. The motion of an object under free fall is an example of which of the following?
[A] uniform velocity
[B] uniform acceleration
[C] zero acceleration
[D] non-uniform acceleration
Show Answer
Correct Answer: B [uniform acceleration]
Notes:
The motion of an object under free fall is a case of uniform acceleration. If an object is released from a height near the surface of earth, it accelerates downwards under the influence of a gravity pull with acceleration due to gravity.
8. What is the relationship between Kinetic and limiting friction?
[A] Kinetic friction is slightly greater than limiting friction
[B] Kinetic friction is slightly less than limiting friction
[C] Kinetic friction is equal to limiting friction
[D] No relationship
Show Answer
Correct Answer: B [Kinetic friction is slightly less than limiting friction]
Notes:
The Kinetic friction is always slightly less than the limiting friction. This is because once the motion has started, the inertia of has been overcome and irregularities of one surface have little or no time to get locked into the irregularities of the other surface.
9. Which of these is/are examples of conservation of linear momentum?
[A] Explosion of bomb
[B] Recoiling of a gun
[C] Fight of rockets and jet planes
[D] All of the above
Show Answer
Correct Answer: D [All of the above]
Notes:Some examples of conservation of linear momentum:
- Recoiling of a gun
- Explosion of bomb
- Fight of rockets and jet planes
- A man jumping out of a boat to the shore
- A person on a frictionless surface
10. At sea level, what is the difference between the value of acceleration due to gravity at the poles and at the equator?
[A] No difference
[B] 9.8 cm s-2
[C] 1.80 cm s-2
[D] None of the above
Show Answer
Correct Answer: C [1.80 cm s-2]
Notes:
At sea level, the difference between the value of acceleration due to gravity at the poles and at the equator is 1.80 cm s-2. The value of acceleration due to gravity increases as we go from equator to the poles.
