Verified past-paper data not yet uploaded
No verified paper has been uploaded for AJKPSC-PMS Paper Physics 2022 MCQs yet.
The MCQs below are drawn from the Physics subject category.
Showing 851–860
of 15721 MCQs
Page 86 / 1573
851
A person moves with a speed thrice the speed of sound waves towards the stationary source of sound. Then the frequency of sound waves heard by the person will:
A. Increase 4 times
B. Increase 3 times
C. Decrease 4 times
D. Decrease 3 times
Discuss
Save
Correct Option
Explanation
Observer moving toward the source at 3v hears frequency f' = f(1 + vo/v) = f(1+3) = 4f, i.e., increases four times.
852
Sound waves do not travel in vacuum because
A. they require material medium for propagation
B. they are transverse waves
C. they are stationary waves
D. they do not have enough energy
Discuss
Save
Correct Option
Explanation
Sound is a mechanical wave and needs a material medium (air, liquid, solid) to propagate, so it cannot travel in vacuum.
853
The unit of intensity level is
A. watt
B. sabin
C. bel
D. joule
Discuss
Save
Correct Option
Explanation
Intensity level (sound level) is commonly measured in bels (or decibels), so bel is the unit for intensity level.
854
The loudness of a sound depends on its
A. wave amplitude
B. regularity
C. wavelength
D. frequency
Discuss
Save
Correct Option
Explanation
Loudness is determined primarily by the amplitude of the sound wave; larger amplitude is perceived as louder.
855
The frequency range for human ear is:
A. 20 KHz-20,000 KHz
B. 20-20,000 Hz
C. 20-20,000 MHz
D. None of these
Discuss
Save
Correct Option
Explanation
The typical audible range for humans is about 20 Hz to 20,000 Hz.
856
Of the material mentioned below the speed of sound is largest in
A. vacuum
B. steel
C. air
D. water
Discuss
Save
Correct Option
Explanation
Sound travels fastest in solids (like steel) because they have higher elastic modulus and can transmit vibrations more rapidly.
857
Increase in velocity of sound in air for 1℃ rise in temperature is
A. 61.0 m s^-1
B. 0.61 m s^-1
C. 1.61 m s^-1
D. 2.00 m s^-1
Discuss
Save
Correct Option
Explanation
The approximate increase in speed of sound in air is about 0.6 m/s per degree Celsius, so 0.61 m/s is correct.
858
A pendulum vibrates with a time period of 1 s. Which range of sound is produced by it?
A. Ultrasonic
B. Infrasonic
C. Supersonic
D. Audible
Discuss
Save
Correct Option
Explanation
A period of 1 s corresponds to frequency 1 Hz, which is below the audible range (<20 Hz), so it is infrasonic.
859
A star emitting yellow light starts moving towards Earth. Its colours as seen from Earth will turn gradually:
A. Blue
B. Orange
C. Red
D. Dark
Discuss
Save
Correct Option
Explanation
Motion towards the observer causes blueshift, so yellow light will shift towards blue as the star approaches.
860
What is shape of a pure note?
A. Sawtooth
B. Triangular wave
C. Sine wave
D. Square wave
Discuss
Save
Correct Option
Explanation
A pure musical note corresponds to a single sinusoidal oscillation, so its waveform is a sine wave.
