Physics Objective (Multiple Choice) General Knowledge & General Science Questions & Answers for SSC-CGL, UPPSC, NDA, CDS and all one day examinations of India.
21. What are the oscillations of a body whose amplitude goes on decreasing with time called as?
[A] Free oscillation
[B] Maintained oscillation
[C] Forced oscillation
[D] Damped oscillation
Show Answer
Correct Answer: D [Damped oscillation]
Notes:
The oscillation of a body whose amplitude goes on decreasing with time are defined as damped oscillation.
22. Which of the following electromagnetic waves are produced due to the radioactive decay of the nucleus?
[A] X-rays
[B] Gamma rays
[C] Radio waves
[D] UV rays
Show Answer
Correct Answer: B [Gamma rays]
Notes:
Gamma rays are produced due to the radioactive decay of the nucleus. Gamma rays have wavelength less than 10–3 nm.
23. What are infrasonic sounds?
[A] Sounds of frequencies below 20 Hz
[B] Sounds of frequencies above 20 Hz
[C] Sounds of frequencies below 200 Hz
[D] Sounds of frequencies above 20 Hz
Show Answer
Correct Answer: A [Sounds of frequencies below 20 Hz]
Notes:
Sounds of frequencies below 20 Hz are called infrasonic sound or infrasound.
24. Which of the following represents Charles’ law?
[A] Volume x Temperature = constant when Pressure is constant
[B] Volume/Temperature = constant when Pressure is constant
[C] Temperature = Volume when Pressure is constant
[D] None of the above
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Correct Answer: B [Volume/Temperature = constant when Pressure is constant]
Notes:
When the pressure is held constant, the volume of a quantity of the gas is related to the temperature as V/T = constant. This relationship is known as Charles’ law.
25. What do we call the ratio of the radiant energy absorbed by a body in a given time to the total radiant energy incident on it in the same time?
[A] Coefficient of volume expansion
[B] Thermal strain
[C] Absorptive power
[D] Radiation limit
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Correct Answer: C [Absorptive power]
Notes:
The ratio of the radiant energy absorbed by it in a given time to the total radiant energy incident on it in the same time is called the absorptive power (a) of the surface.
26. What do we call the temperature at which the liquid and the vapour states of the substance coexist?
[A] Freezing point
[B] Melting point
[C] Boiling point
[D] Normal point
Show Answer
Correct Answer: C [Boiling point]
Notes:
The temperature at which the liquid and the vapour states of the substance coexist is called its boiling point.
27. What is the S.I unit of Latent heat of fusion?
[A] J kg-1 K-1
[B] J kg-2
[C] J kg K-1
[D] J kg-1
Show Answer
Correct Answer: D [J kg-1]
Notes:
The latent heat for a solid liquid state change is called the latent heat of fusion The S.I. unit of the latent heat of fusion is J kg-1.
28. Which of the following is correct about Permeability of free space?
[A] It is a scalar quantity
[B] Its S.I unit is T m A-1
[C] Both a and b
[D] None of the above
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Correct Answer: C [Both a and b]
Notes:
The Permeability of free space is a scalar quantity and its S.I. unit is T m A-1.
29. What happens to a bar magnet of dipole moment (m) is placed in a uniform magnetic field (B)?
[A] the force on the bar magnet is zero
[B] the torque on the bar magnet is m × B
[C] Both a and b
[D] None of the above
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Correct Answer: C [Both a and b]
Notes:
When a bar magnet of dipole moment m is placed in a uniform magnetic field B: (a) the force on it is zero, (b) the torque on it is m × B, (c) its potential energy is –m.B, where we choose the zero of energy at the orientation when m is perpendicular to B.
30. Which of these rays have the highest penetrating power?
[A] Alpha
[B] Beta
[C] Gamma
[D] All have the same
Show Answer
Correct Answer: C [Gamma]
Notes:
Gamma rays have the highest penetrating power followed by Beta and the Alpha.
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