Sound(8th Grade > Physics ) Questions and answers for exam Preparation

8th Grade > Physics

SOUND MCQs

Total Questions : 55 | Page 5 of 6 pages

Question 41.

The amplitude of a sound wave determines its ___.

pitch
loudness
wavelength
frequency

Discuss Question

Answer: Option B. -> loudness
:
B

The amplitude of a sound wave is the maximum distance of a crest or a trough from the mean line. It determines the loudness of the sound. Greater the amplitude, greater will be the loudness.

Question 42.

A drum vibrates with a lower frequency as compared to a whistle. Then, we can say that:

The sound produced by the drum is louder than the whistle.
The sound produced by the whistle is louder than the drum.
The sound produced by the drum has a higher pitch than the whistle.
The sound produced by the whistle has a higher pitch than the drum.

Discuss Question

Answer: Option D. -> The sound produced by the whistle has a higher pitch than the drum.
:
D

The pitch of a sound depends on its frequency. It is given, the frequency of the drum is lower than that of the whistle. Hence, the drum produces a lower pitched sound as compared to the whistle.

Question 43.

Which of the following units can be used to measure the frequency of a sound wave?

hertz
second
second $^{- 1}$
metre

Discuss Question

Answer: Option A. -> hertz
:
A and C
The number of waves produced per unit time is called frequency

(f)

. The time taken to produce one complete wave is called timeperiod

(T)

. The frequency of a wave is equal to inverse of timeperiod i.e,

f

\frac{1}{T}

.
The SI unit of frequency is hertz (Hz).
1 Hz = 1 s

^{- 1}

Question 44.

Ultrasonic sound have frequency ___.

below 20 Hz
between 20-2,000 Hz
between 2,000-20,000 Hz
above 20,000 Hz

Discuss Question

Answer: Option D. -> above 20,000 Hz
:
D
Ultrasonic refers to sound having frequency higher than the upper audible limit of human hearing. It has frequency above 20,000 Hz.

Question 45.

If a longitudinal wave is travelling in the west direction, what can be the possible direction of the vibration of particles of the medium?

East-west
Up-down
North-south
Medium needs to be specified

Discuss Question

Answer: Option A. -> East-west
:
A
In a longitudinal wave, particles of the medium vibrate parallel to the direction of wave propagation. As the given wave is travelling in the west direction, the particles will also vibrate along the east-west direction.

Question 46.

We can hear the sound produced by a meteorite strike on the moon's surface.

True
False

Discuss Question

Answer: Option B. -> False
:
B

Sound cannot propagate through vacuum. As there is no atmosphere on the moon, sound waves cannot be heard and the given statement is false.

Question 47.

Which of the following are sources of noise pollution?

Airplanes
Heavy machines
Silencers
Loudspeakers

Discuss Question

Answer: Option B. -> Heavy machines
:
A, B, and D

Noise is unwanted sound which is unpleasant to ears. Following are some of the sources of noise pollution:

Heavy machines

Airplanes

Loud speakers

Old vehicles

Silencers are devices used to control noise pollution by reducing sound intensity.

Question 48.

What is the function of cochlea in a human ear?

It protects the ear from damage.
It converts ear drum vibrations into electrical impulses.
It amplifies vibrations reaching the middle ear.
It directs sound waves into the ear canal.

Discuss Question

Answer: Option B. -> It converts ear drum vibrations into electrical impulses.
:
B
The cochlea is a snail shell-like structure present in the inner ear that converts the vibrations of the ear drum or the tympanic membrane into electrical impulses. These electrical signals are then transmitted to the brain via the auditory nerve which then will aid us in hearing.

What Is The Function Of Cochlea In A Human Ear?

Question 49.

A boy is running to and fro between points A and B with a constant speed of 20 m/s. If the points A and B are 5 m apart, find the frequency of to and fro motion of the boy.