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. Edwin Howard Armstrong was an inventor of which of the following technologies?
[A] Television
[B] Compact Discs
[C] FM Radio
[D] Broadband
Show Answer
Correct Answer: C [FM Radio]
Notes:
Edwin Howard Armstrong was an American electrical engineer who developed FM radio and the superheterodyne receiver system. Edwin Howard Armstrong is the “father of FM radio” and was born in 1890.
2. In recent times, the “dynamic brake system” is becoming popular in modern railways. The dynamic brake system coverts Kinetic energy to__:
[A] Potential energy
[B] Electricity
[C] Sound energy
[D] Magnetic energy
Show Answer
Correct Answer: B [ Electricity]
Notes:
Modern engines also have, additionally, dynamic brake system which works on the principle of converting kinetic energy of the moving train to electricity making the electric motors to work as generators.
3. When you throw a ball with an angle to the horizontal (projectile); the ball has __:
[A] Uniform velocity in horizontal direction but uniform acceleration in vertical direction
[B] Uniform acceleration in horizontal direction but uniform velocity in vertical direction
[C] Uniform acceleration in both horizontal and vertical directions
[D] Uniform velocity in both horizontal and vertical directions
Show Answer
Correct Answer: A [ Uniform velocity in horizontal direction but uniform acceleration in vertical direction]
Notes:
The motion of a projectile is two dimensional motion consisting of (i) horizontal motion and (ii) vertical motion. Hence, at any instant, the velocity of a projectile has two components (i) horizontal component and (ii) vertical component. The horizontal component remains unchanged throughout the flight as there is no acceleration in horizontal direction. The vertical component is continuously affected by the force of gravity. Thus, the horizontal motion is uniform motion but the vertical motion is uniformly accelerated motion.)
4. 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.
5. The recoiling of gun is an example of which of the following?
[A] Law of Conservation of Angular Momentum
[B] Law of Conservation of Linear Momentum
[C] Conversion of Kinetic Energy to Potential Energy
[D] Law of Conservation of Energy
Show Answer
Correct Answer: B [Law of Conservation of Linear Momentum]
Notes:
The recoiling of gun is an example of Law of Conservation of Linear Momentum. When gun fires a bullet, it experiences a force in forward direction (action) , as a result the gun exerts a backward force (reaction) on the shoulder. Thus, it is in accordance with Law of Conservation of Linear Momentum which is also the Newton’s 3rd law of motion.
6. The thrust on the rocket is:
[A] in the same direction of the rocket
[B] in the opposite direction of the rocket
[C] at 90° to the direction of the rocket
[D] None of the above
Show Answer
Correct Answer: B [in the opposite direction of the rocket]
Notes:
The thrust on the rocket is in the opposite direction of the rocket. The thrust is the force with which rocket moves upwards. F = -u (dm/dt)
7. 1 kilogram force produces how much acceleration in a body of mass 1 kg?
[A] 1 ms-2
[B] 0
[C] 9.8 ms-2
[D] -1 ms-2
Show Answer
Correct Answer: C [9.8 ms-2]
Notes:
1 Kilogram force or 1 Kilogram weight is that much force which produces an acceleration of 9.8 ms-2 in a body of mass 1 kg. Also, 1 kg wt. or 1 kg f = 9.8 N
8. Which of the following is NOT correct about an inelastic collision?
[A] Linear momentum is conserved
[B] Kinetic energy is conserved
[C] Total energy is conserved
[D] Some or all the forces involved may be non-conservative in nature
Show Answer
Correct Answer: B [Kinetic energy is conserved]
Notes:
Following are the basic characteristics of an inelastic collision: 1. Linear momentum is conserved 2. Kinetic energy is NOT conserved 3. Total energy is conserved 4. Some or all the forces involved may be non-conservative in nature
9. Work done will NOT be zero in which of the following case/cases?
[A] When displacement is zero
[B] When angle between force and displacement vector is zero
[C] When angle between force and displacement vector is 90°
[D] When force is zero
Show Answer
Correct Answer: B [When angle between force and displacement vector is zero]
Notes:
Work done will be zero: 1. When displacement is zero 2. When force is zero 3. When angle between force and displacement vector is zero
10. What will be the work done in holding a 25 kg iron plate for 25 seconds?
[A] 25 j
[B] 1 j
[C] 0
[D] 625 j
Show Answer
Correct Answer: C [0]
Notes:
The work done in holding a 25 kg iron plate for 25 seconds will be zero as there is no displacement taking place. Work done = Force x Displacement
