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 principle is used by Bats?
[A] RADAR (Radio Detective & Ranging
[B] SONAR (Sound Navigation & Ranging
[C] law of reflection
[D] law of diffraction
Show Answer
Correct Answer: B [SONAR (Sound Navigation & Ranging]
Notes:
Bats use SONAR (Sound Navigation & Ranging).Sonar is a technique that uses sound propagation to navigate, communicate with or detect objects on or under the surface of the water, such as other vessels.
2. Where will the weight of a person be maximum?
[A] At the Poles
[B] At the Tropic of Capricorn
[C] At the Tropic of Cancer
[D] At the Equator
Show Answer
Correct Answer: A [At the Poles]
Notes:
The weight of a person would be maximum at the poles, due to the higher gravitational force acting upon them in these regions. This occurs because Earth is an oblate spheroid, flattened at its poles and bulging at the equator, resulting in a shorter distance from the Earth’s center at the poles and a consequent higher gravitational pull. At the equator, the force is slightly weaker due to a greater distance from the Earth’s center. Weights at the Tropics of Cancer and Capricorn lie in-between the poles and equator, but are closer to the equator’s value.
3. Which among the following orbits are more prone to harms of space debris or space Junk in comparison to others?
[A] Polar Sun Synchronous Orbit
[B] Low Earth Orbit
[C] Geosynchronous orbit
[D] Geostationary Orbit
Show Answer
Correct Answer: D [ Geostationary Orbit]
Notes:
Low Earth Orbit (LEO) is more prone to space debris or space junk. This is because space debris is more concentrated in orbits closer to Earth. Most debris is within 2,000 km (1,200 miles) of Earth’s surface.
Space debris orbits the Earth at tremendous speeds, about 15,700 miles per hour (25,265 kph) in low Earth orbit. In the event of a collision, it could cause significant damage to a satellite or spacecraft.
Experts are concerned about the amount of space debris in regions that are too high to benefit from the cleansing effects of Earth’s atmosphere. They believe that if there is too much space junk in orbit, it could result in a chain reaction where more and more objects collide and create new space junk.
4. What is the change in the angular momentum of a system as per the Law of Conservation of Angular momentum, if the total external torque acting is zero?
[A] Remains constant
[B] Becomes zero
[C] Increases exponentially
[D] None of the above
Show Answer
Correct Answer: A [Remains constant]
Notes:
Law of Conservation of Angular Momentum: if the total external torque acting on a system is zero, the angular momentum of a system remains constant. Angular Momentum is the momentum associated with the rotation of an object. Angular Momentum = moment of Inertia X angular Speed
5. What is the value of Triple point of water?
[A] 273.16 K
[B] 273.16° C
[C] 0° C
[D] -273.16 K
Show Answer
Correct Answer: A [ 273.16 K ]
Notes:
Triple point of water is the temperature at which ice, water and water vapours coexist. The value of Triple point of water is 273.16 K Kelvin is the S.I unit of Temperature represented by symbol K.
6. The magnitude of the resultant of two vectors is maximum in which of the following case?
[A] when vectors act in the same direction
[B] when vectors act in the opposite direction
[C] when vectors act at 90° to each other
[D] None of the above
Show Answer
Correct Answer: A [when vectors act in the same direction]
Notes:
The magnitude of the resultant of two vectors is maximum when vectors act in the same direction. The magnitude of the resultant of two vectors is minimum when vectors act in the opposite directions.
7. What happens to the velocity of a light body when it undergoes an elastic collision in one dimension with a very heavy body at rest?
[A] its velocity becomes twice
[B] it rebounds with twice of its own velocity
[C] it rebounds with its own velocity
[D] it stops and comes to rest
Show Answer
Correct Answer: C [it rebounds with its own velocity]
Notes:
A light body rebounds with its own velocity when it undergoes an elastic collision in one dimension with a very heavy body at rest. Note: The heavy body continues to be in rest in this case
8. What is the dimensional formula of Gravitational Potential?
[A] M1 L2 T-2
[B] M1 L-2 T2
[C] M0 L2 T-2
[D] M0 L2 T2
Show Answer
Correct Answer: C [M0 L2 T-2]
Notes:
The dimensional formula of Gravitational Potential is M0 L2 T-2 It is a scalar quantity. S.I. units of Gravitational Potential is J/kg
9. What is the gravitational potential energy for infinite distance?
[A] 0
[B] infinity
[C] 9.8 J
[D] None of the above
Show Answer
Correct Answer: A [0]
Notes:
The gravitational potential energy of a body at a point is defined as the amount of work done in bringing the body from infinity to that point against the gravitational force. U = – GMm/r When r =infinity, then U =0
10. Which of the following is correct about the value of acceleration due to gravity?
[A] it is greater at mountains than in plains
[B] it is lesser at mountains than in plains
[C] it is equal for mountains and plains
[D] None of the above
Show Answer
Correct Answer: B [it is lesser at mountains than in plains]
Notes:
The value of acceleration due to gravity decreases with increase in height. Therefore, it is lesser at mountains than in plains.
