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.
11. What is the stress known as when there is a relative displacement between various layers of solid?
[A] Tangential
[B] Linear
[C] Lateral
[D] Longitudinal
Show Answer
Correct Answer: A [Tangential]
Notes:
When successive layers of solid move on each other i.e. when there is a relative displacement between various layers of solid, the stress produced is called as Tangential stress.
12. What is the maximum stress after which the wire breaks called as?
[A] Tensile strength
[B] Shear strength
[C] Bulk strength
[D] Hooke’s strength
Show Answer
Correct Answer: A [Tensile strength]
Notes:
The maximum stress after which the wire begin to flow and breaks, is called breaking stress or tensile strength. The force by application of which the wire breaks is called the breaking force.
13. Who invented mercury barometer?
[A] Blaise Pascal
[B] Daniel Bernoulli
[C] Albert Einstein
[D] Evangelista Torricelli
Show Answer
Correct Answer: D [Evangelista Torricelli]
Notes:
Evangelista Torricelli devised for the first time a method for measuring atmospheric pressure. A long glass tube closed at one end and filled with mercury is inverted into a trough of mercury. This device is known as ‘mercury barometer’.
14. Which is correct about the height of a capillary column of a liquid, at a particular temperature, as per Jurin’s law?
[A] equal to the diameter of the tube
[B] directly proportional to the diameter of the tube
[C] inversely proportional to the diameter of the tube
[D] half of the diameter of the tube
Show Answer
Correct Answer: C [inversely proportional to the diameter of the tube]
Notes:
Jurin’s law: the height of a capillary column of a liquid at a particular temperature is inversely proportional to the diameter of the tube.
15. What will be the change in the height of water in a capillary tube in stationary condition on earth if the same tube is taken in a lift going downward with acceleration?
[A] height increases
[B] height decreases
[C] Remains same
[D] can decrease or increase
Show Answer
Correct Answer: A [height increases]
Notes:
In a lift going downward with acceleration, the effective acceleration decreases. So height increases as height is inversely proportional to the acceleration due to gravity.
16. What is the speed of electromagnetic waves in vacuum?
[A] 1000 m/s
[B] 3 x 108 m/s
[C] 300000 m/s
[D] Different for different waves
Show Answer
Correct Answer: B [3 x 108 m/s]
Notes:
In vacuum, all electromagnetic waves have the same speed whose value is 299, 792, 458 m/s or nearly equal to 3 x 108 m/s.
17. Which of the following is NOT a mechanical wave?
[A] Sound wave
[B] Seismic wave
[C] Light wave
[D] Water waves
Show Answer
Correct Answer: C [Light wave]
Notes:
Sound wave, seismic wave and water waves are mechanical waves whereas light wave is an electromagnetic wave.
18. Which of the following represents the speed of a sound wave?
[A] wavelength x frequency
[B] 2 x wavelength x frequency
[C] wavelength/frequency
[D] (wavelength x frequency)/2
Show Answer
Correct Answer: A [wavelength x frequency]
Notes:
The speed of sound is defined as the distance which a point on a wave, such as a compression or a rarefaction, travels per unit time. It is represented by s = wavelength x frequency.
19. Which of the following represents the absolute zero temperature?
[A] 0° C
[B] -100° C
[C] -273.15° C
[D] 273.15° C
Show Answer
Correct Answer: C [-273.15° C]
Notes:
This temperature is found to be –273.15 °C and is designated as absolute zero. This is the absolute minimum temperature for an ideal gas.
20. What do we call a device by which a system is made to undergo a cyclic process resulting in conversion of heat to work?
[A] Heat engine
[B] Refrigerator
[C] No such device exists
[D] None of the above
Show Answer
Correct Answer: A [Heat engine]
Notes:
Heat engine is a device by which a system is made to undergo a cyclic process that results in conversion of heat to work.
