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 measured using a Vernier Caliper?
[A] Dimensions
[B] Time
[C] Sound
[D] Temperature
Show Answer
Correct Answer: A [Dimensions]
Notes:
The Vernier caliper has a main scale and a sliding vernier scale which can measure nearest to 0.02 mm. It can be used to measure internal and the external dimensions of an object by using the smaller jaws at the top and the main jaws respectively. By using stems depth can be measured.
2. On which of the following the jet Engine works?
[A] Conservation of energy
[B] Conservation of Linear Momentum
[C] Conservation of Mass
[D] Conservation of Angular momentum
Show Answer
Correct Answer: B [Conservation of Linear Momentum]
Notes:Conservation of Linear Momentum law says that if no external force acts on a system, then its total linear momentum remains conserved. In equation form, Momentum=mass*velocity. To increase the momentum of an object, we need to either increase its mass or velocity or both.
- Rockets work on law of conservation of momentum. As momentum in one direction is given to the rocket’s exhaust gases, momentum in the other direction is given to the rocket itself.
3. Two pieces of ice at 0°C would freeze together if pressed against each other and then released. In this context, which among the following is the correct principle in action in this?
[A] The melting point of pure ice decreases with pressure.
[B] The melting point of pure ice increases with Pressure
[C] The melting point of pure ice first increases, then decreases with pressure
[D] The melting point of pure ice first decreases then increases with pressure
Show Answer
Correct Answer: A [ The melting point of pure ice decreases with pressure.]
Notes:
Melting point of pure ice decreases with pressure at the rate of 0.0072°C per atmosphere and this is called regulation, which was discovered by Faraday and occurs at some 0°C or very slightly less temperature.
4. On heating a pure silicon circular disc with a circular hole at the centre, the diameter of the hole:
[A] will expand
[B] will contract
[C] will remain constant
[D] may expand or contract
Show Answer
Correct Answer: B [ will contract]
Notes:
Pure silicon has a negative coefficient of thermal expansion for temperatures and hence it shows contraction effect.
5. What is the range of masses involved in the study of Physics?
[A] 10-19 kg to 1038 kg
[B] 10-30 kg to 1055kg
[C] 10-30 kg to 1030kg
[D] 10-19 kg to 1055 kg
Show Answer
Correct Answer: B [10-30 kg to 1055kg]
Notes:
The range of masses involved in the study of Physics ranges from 10-30 kg to 1055 kg. 10-30kg is the mass of an electron and 1055 kg is the mass of known observable universe. The range of time scale involved in the study of Physics ranges from 10-22 s to 1018 s. The range of length involved in the study of Physics ranges from 10-14m to 1026 m.
6. Which of the following is the unit of Solid Angle?
[A] radian
[B] steradian
[C] m2
[D] π
Show Answer
Correct Answer: B [ steradian ]
Notes:
Steradian is the unit of Solid Angle (Angle in Space). One steradian is defined as the solid angle of a sphere subtended at the centre of a sphere by that surface of the surface whose area is equal to the square of the sphere’s radius. Its symbol is sr.
7. 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°.
8. The equation of motion ‘v = u +at’ can be applied in which of the following cases?
[A] simple harmonic motion
[B] circular motion
[C] when acceleration is constant
[D] Both b and c
Show Answer
Correct Answer: C [when acceleration is constant]
Notes:
The equation of motion ‘v = u +at’ can be applied only when the acceleration is constant. It cannot be applied in the cases of simple harmonic motion and circular motion.
9. Which of the following is NOT a method to reduce friction?
[A] By lubrication
[B] By polishing
[C] throwing sand on the ground
[D] None of the above
Show Answer
Correct Answer: C [throwing sand on the ground]
Notes:
Some of the ways of reducing friction are: 1. By polishing 2. By lubrication 3. By proper selection of materials 4. By streamlining 5. By using ball bearings
10. Which of the following is an example of application of force?
[A] when a body at rest starts moving
[B] when a moving body stops
[C] when moving body changes its direction
[D] All of the above
Show Answer
Correct Answer: D [All of the above]
Notes:
Force can be defined as an external effort in the form of push or pull which: (i) Produces or tries to produce motion in a resting body (ii) Stops or tries to stop a moving body (iii) Changes or tries to change the direction of motion of the body
