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.
21. Which of the following is NOT an example of capillary action?
[A] Rise of ink in the fine pores of blotting paper
[B] soaking of water by a towel
[C] Wood swells in rainy season due to rise of moisture
[D] None of the above
Show Answer
Correct Answer: D [None of the above]
Notes:
Examples of capillarity : (i) Ink rises in the fine pores of blotting paper leaving the paper dry. (ii) A towel soaks water. (iii) Oil rises in the long narrow spaces between the threads of a wick. (iv) Wood swells in rainy season due to rise of moisture from air in the pores.
22. What is the SI unit of viscosity?
[A] candela
[B] poiseiulle
[C] Newton/m
[D] No units
Show Answer
Correct Answer: B [poiseiulle]
Notes:
The SI unit of viscosity is poiseiulle (Pl). Its other units are N s m-2 or Pa s.
23. What is the S.I unit of frequency?
[A] Second
[B] Watt
[C] Hertz
[D] Joule
Show Answer
Correct Answer: C [Hertz]
Notes:
The frequency is defined as the number of periodic motions executed by body per second. The S.I unit of frequency is hertz (Hz).
24. In which of the following positions is the kinetic energy maximum in S.H.M?
[A] Extreme position
[B] Mean position
[C] Can be at extreme or mean position
[D] None of the above
Show Answer
Correct Answer: B [Mean position]
Notes:
Kinetic energy is maximum at mean position and equal to total energy at mean position. Kinetic energy is minimum at extreme position.
25. What is the oscillation in which the loss of oscillator is compensated by the supplying energy from an external source known as?
[A] Free oscillation
[B] Maintained oscillation
[C] Forced oscillation
[D] Damped oscillation
Show Answer
Correct Answer: B [Maintained oscillation]
Notes:
The oscillation in which the loss of oscillator is compensated by the supplying energy from an external source are known as maintained oscillation.
26. What are ultrasonic sounds?
[A] Sounds of frequencies above 2 KHz
[B] Sounds of frequencies above 20 KHz
[C] Sounds of frequencies above 200 KHz
[D] Sounds of frequencies above 20 Hz
Show Answer
Correct Answer: B [Sounds of frequencies above 20 KHz]
Notes:
Sounds with frequencies higher than 20 kHz are called ultrasonic sound or ultrasound. Ultrasound is produced by dolphins, bats and porpoises.
27. Which of the following conditions will not show any Doppler effect?
[A] When source and listener both are at rest
[B] When medium alone is moving
[C] When source and listener are moving in mutually perpendicular directions
[D] All of the above
Show Answer
Correct Answer: D [All of the above]
Notes:
Conditions for no Doppler effect : (i) When source (S) and listener (L) both are at rest. (ii) When medium alone is moving. (iii) When S and L move in such a way that distance between S and L remains constant. (iv) When source S and listener L, are moving in mutually perpendicular directions
28. Which of the following represents Boyle’s law?
[A] Pressure = Volume when temperature is constant
[B] Pressure x Volume = constant when temperature is constant
[C] Pressure =2 x Volume when temperature is constant
[D] None of the above
Show Answer
Correct Answer: B [Pressure x Volume = constant when temperature is constant]
Notes:
When temperature is held constant, the pressure and volume of a quantity of gas are related as PV = constant. This relationship is known as Boyle’s law
29. What is the value of universal gas constant?
[A] 2.31 J mol-1 K–1
[B] 4.31 J mol-1 K–1
[C] 6.31 J mol-1 K–1
[D] 8.31 J mol-1 K–1
Show Answer
Correct Answer: D [8.31 J mol-1 K–1]
Notes:
As per the ideal gas equation, PV = nRT where R is the Universal Gas constant and has a value of 8.31 J mol-1 K–1.
30. Which of the following is correct about the rate of loss of heat of the body, as per the Newton’s law of cooling?
[A] It is directly proportional to the difference of body’s temperature and the surroundings
[B] It is inversely proportional to the difference of body’s temperature and the surroundings
[C] It is equal to the difference of body’s temperature and the surroundings
[D] None of the above
Show Answer
Correct Answer: A [It is directly proportional to the difference of body’s temperature and the surroundings]
Notes:
According to Newton’s law of cooling, the rate of loss of heat, – dQ/dt of the body is directly proportional to the difference of temperature of the body and the surroundings.
