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. If in a closed room , the door of a refrigerator is kept open for some time , the temperature of room will ?
[A] Increase
[B] Decrease
[C] Remains same
[D] First decrease then become stable
Show Answer
Correct Answer: A [Increase]
Notes:
A refrigerator is like a heat engine. It extracts heat from low temperature reservoir and transfer it to high temperature. If a refrigerator’s door is kept open, then room will become hot, because then refrigerator exhaust more heat into the room than earlier.
2. Which among the following is true about conduction, convection and radiation mode of transfer of heat?
[A] A Medium is required for conduction but not required for convection and radiation
[B] A medium is required for conduction, convection and radiation
[C] A medium is required for conduction and convection but not required for radiation
[D] A medium is not required for conduction and convectio, radiation
Show Answer
Correct Answer: C [A medium is required for conduction and convection but not required for radiation]
Notes:
A medium is required for conduction and convection but not required for radiation. The radiation can occur even in vaccum but not the others. The conduction can travel through solid. The convection process needs liquid and gas.
3. 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.
4. “Svedberg Unit” is a measure of?
[A] Concentration
[B] Size
[C] Density
[D] Time
Show Answer
Correct Answer: D [Time]
Notes:
A Svedberg unit (S/ Sv) is utilized to denote sedimentation coefficients, providing specific measurement of a particle based on its sedimentation rate under acceleration. Essentially, it computes how quickly a particle settles to the bottom of a solution. In terms of the time dimension, a Svedberg unit amounts to exactly 10−13 seconds, indicating that it is essentially a measure of time.
5. A long Rail (approximately 700 meters) made up of steel is struck to produce a sound. The person standing on the other end of the rail would hear in which among the following pattern?
[A] He listens the sound waves once propagated via steel
[B] He listens the sound waves once propagated via air
[C] He listens the sound waves twice, first propagated via steel and second propagated via air
[D] He listens the sound waves twice, first propagated via air and second propagated via steel
Show Answer
Correct Answer: C [He listens the sound waves twice, first propagated via steel and second propagated via air]
Notes:
The correct answer is that the person hears the sound waves twice: first via steel and then via air. Sound travels faster in solids than in gases. in steel, it travels at about 5,960 m/s, while in air, it travels at approximately 343 m/s. Given the long distance of 700 meters, the sound will reach the person through the steel rail first, followed by the sound traveling through the air. This phenomenon illustrates the differences in sound propagation speeds in different media.
6. 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.
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. 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.
9. Two satellites, A having mass of 500 kgs and B having mass of 1200 kgs, are launched from earth. Which of these will have a greater orbital velocity if the radius of orbit is same for both?
[A] Satellite A
[B] Satellite B
[C] Both satellites will have the same orbital velocity
[D] Cant be determined
Show Answer
Correct Answer: C [Both satellites will have the same orbital velocity]
Notes:
Both satellites will have the same orbital velocity as the orbital velocity of a satellite is independent of mass of satellite.
10. What happens to a body when its density is equal to the density of the fluid?
[A] it floats
[B] it sinks
[C] it remains suspended
[D] None of the above
Show Answer
Correct Answer: C [it remains suspended]
Notes:
If the buoyant force equals the object’s weight, the object will remain suspended at that depth. If the buoyant force is greater than the object’s weight, the object will rise to the surface and float. If the buoyant force is less than the object’s weight, the object will sink. The buoyant force is always present whether the object floats, sinks, or is suspended in a fluid.
