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 of the following statements is incorrect about a Plane Mirror?
[A] The focal length of a plane mirror is infinity
[B] Its optical power is one
[C] It forms a virtual image of a real object
[D] It is used in constructing periscope
Show Answer
Correct Answer: B [Its optical power is one]
Notes:
Second statement is incorrect because the optical power of plane mirror is zero.
2. Who among the following is known to manufacture first Cyclotron?
[A] Ernest Lawrence
[B] Niels Bohr
[C] Rutherford
[D] Max Born
Show Answer
Correct Answer: A [Ernest Lawrence]
Notes:
A cyclotron is a type of particle accelerator invented by Ernest O. Lawrence in 1929–1930 at the University of California, Berkeley, and patented in 1932. A cyclotron accelerates charged particles outwards from the center along a spiral path.
3. You are sitting inside an open vehicle moving with uniform speed. When you throw a stone vertically upwards, the stone will fall__:
[A] Ahead of you
[B] Behind you
[C] Over you
[D] Either ahead or behind of you
Show Answer
Correct Answer: C [ Over you]
Notes:
Uniform speed means no acceleration. If there is no acceleration and the vehicle is moving with uniform speed; the stone will fall over you.
4. 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.
5. The centripetal force and centrifugal force are ______:
[A] equal in magnitude and have same direction
[B] unequal in magnitude and have same direction
[C] equal in magnitude and have opposite direction
[D] unequal in magnitude and have opposite direction
Show Answer
Correct Answer: C [equal in magnitude and have opposite direction]
Notes:
The centripetal force and centrifugal force are equal in magnitude and have opposite direction. Centrifugal force can be regarded as the reaction of centripetal force.
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. Which of the following is NOT a conservative force?
[A] Electrostatic force
[B] Magnetic force
[C] Force in an elastic spring
[D] Frictional force
Show Answer
Correct Answer: D [Frictional force]
Notes:
A conservative force is a force with the property that the work done in moving a particle between two points is independent of the taken path. Examples: Electrostatic force, Magnetic force, Force in an elastic spring Frictional force is a non-conservative force.
8. The capacity of a body to do work is known as:
[A] Energy
[B] Power
[C] Momentum
[D] Strength
Show Answer
Correct Answer: A [Energy]
Notes:
Energy of a body is the capacity or the ability of a body to do the work. Energy is a scalar quantity having magnitude but no direction. Its unit is same as that of Work S.I. unit: joule In c.g.s system, unit is erg.
9. What is the value of escape velocity for earth?
[A] 9.8 km s-2
[B] 1.6 km s-2
[C] 11.2 km s-2
[D] 7.92 km s-2
Show Answer
Correct Answer: C [11.2 km s-2]
Notes:
The value of escape velocity is different for different planets. For earth, this value is 11.2 km s-2.
10. On which of the following the escape velocity of a body does not depend?
[A] Mass of the body
[B] Radius of the planet
[C] Mass of the planet
[D] None of the above
Show Answer
Correct Answer: A [Mass of the body]
Notes:
The escape velocity is independent of the mass and angle of projection of the body. Escape velocity depends on the mass and radius of the planet from the surface of which the body is to be projected.
