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 frequency range characterizes Ultrasound, that is beyond the upper limit of human auditory perception?
[A] Above 20 KHz
[B] Above 200 KHz
[C] Above 2 KHz
[D] Below 20 KHz
Show Answer
Correct Answer: A [Above 20 KHz]
Notes:
Ultrasound corresponds to sound waves with frequencies exceeding the upper limit of human perceptible sound, generally above 20 kHz. Humans, typically, can perceive sounds ranging between 20 Hz and 20 kHz. Ultrasound, therefore, is beyond the auditory range of humans and is employed in technologies like medical imaging and sonar devices due to its unique properties.
2. 1 nautical mile is equivalent to which of the following?
[A] 1.44 x 1000 m
[B] 1.852 x 100 m
[C] 1.852 x 1000 m
[D] 1.44 x 100 m
Show Answer
Correct Answer: C [ 1.852 x 1000 m ]
Notes:nautical mile is a unit of length. 1 nautical mile is equal to 1.852 x 1000 m Other important units of length are:
- 1 mile = 1.609 x 1000 m
- 1 light year = 9.46 x 1015 m
- 1 AU = 1.5 x 1011m
- 1 Par sec = 3.1 x 1016m
3. What is the absolute unit of power in c.g.s system?
[A] dyne
[B] erg
[C] watt
[D] erg s-1
Show Answer
Correct Answer: D [erg s-1]
Notes:
Power is defined as the rate of doing work. The absolute unit of power in c.g.s system is erg s-1 The absolute unit of power in S.I system is watt 1 watt = 1 joule/sec 1 kW= 1000 watt 1 h.p = 746 W
4. Which of the following represents the dimensional formula of Universal Gravitational Constant?
[A] M1 L2 T-2
[B] M-1 L1 T-2
[C] M-1 L3 T-2
[D] M1 L3 T-2
Show Answer
Correct Answer: C [M-1 L3 T-2]
Notes:
The dimensional formula of Universal Gravitational Constant is M-1 L3 T-2 Universal Gravitational Constant is a scalar quantity.
5. Which of the following is correct about Gravitational force?
[A] It is always attractive in nature
[B] It is always repulsive in nature
[C] It may or may not be attractive in nature
[D] None of the above
Show Answer
Correct Answer: A [It is always attractive in nature]
Notes:
The Gravitational force is always attractive in nature while electric and magnetic force can be attractive or repulsive. It is the weakest force in nature.
6. The angular momentum of a satellite depends on which of the following?
[A] Mass of the satellite
[B] Mass of the planet
[C] Radius of orbit of satellite
[D] All of the above
Show Answer
Correct Answer: D [All of the above]
Notes:
The angular momentum of a satellite depends on: 1. Mass of the satellite 2. Mass of the planet 3. Radius of orbit of satellite it is denoted by L. L = (m2GMr)1/2
7. Water does not fall out of a glass when it is inverted inside a satellite, which is orbiting very close to the earth’s surface. Which of the following is the best reason for this?
[A] The earth does not exert any force on the water
[B] The earth’s force of attraction on the water is exactly balanced by the force created by the satellites
[C] The water and the glass have the same acceleration due to gravity
[D] The gravitational attraction between the glass and the water balances the earth’s attraction on the
Show Answer
Correct Answer: C [The water and the glass have the same acceleration due to gravity]
Notes:
Water does not fall out of a glass when it is inverted inside a satellite, which is orbiting very close to the earth’s surface. The reason for this is that the water and the glass have the same acceleration due to gravity, equal to g, towards the centre of the earth. Hence there is no relative motion between them.
8. Which of the following relations between Kinetic energy and Potential energy is true about solids?
[A] Kinetic energy = Potential energy
[B] Kinetic energy > Potential energy
[C] Kinetic energy >> Potential energy
[D] Kinetic energy < Potential energy
Show Answer
Correct Answer: D [Kinetic energy < Potential energy]
Notes:
In Solids, Kinetic energy is always less than the Potential energy. For liquids, Kinetic energy > Potential energy. For Gases, Kinetic energy >> Potential energy.
9. What is the unit of Stress?
[A] N/m
[B] Kg/m
[C] Nm
[D] It has no units
Show Answer
Correct Answer: A [N/m]
Notes:
If an external force F is applied on the area A of a body then, Stress is given by Force/Area Units of Stress: S.I unit: N / m C.g.s unit: dyne / cm
10. Which of the following equation represents the Torricelli’s law?
[A] (2gh)1/2
[B] √3 gh
[C] √2 gh
[D] 2gh
Show Answer
Correct Answer: A [(2gh)1/2]
Notes:
Torricelli’s theorem is also called as Torricelli’s law, It states that the speed, v, of a liquid flowing under the force of gravity out of an opening in a tank is proportional jointly to the square root of the vertical distance, h, between the liquid surface and the centre of the opening and to the square root of double the acceleration due to gravity. V = (2gh)1/2
