Free Sound 02 Practice Test - 8th Grade 

Question 1

Two sound waves - A and B are travelling in air. If wave A has a time period of 2 s and an amplitude of 3 cm and wave B has a time period of 3 s and an amplitude of 11 cm, which of the following statements are correct?

A. Wave A is louder than wave B.
B. Wave B has a lower pitch than wave A.
C. Wave A has a lower pitch than wave B.
D. Wave B is louder than wave A.

SOLUTION

Solution : B and D

The pitch of a sound depends on its frequency. Higher the pitch, higher the frequency. Also, frequency is equal to the inverse of time period. So, if the time period of a wave is more, it means its frequency is less, and hence it also has a lower pitch. So, wave B has a lower pitch than wave A.

Loudness depends on the amplitude. Larger the amplitude, louder is the sound. So, wave B is louder than wave A.

Question 2

Sound can travel through _____________.

A.

 gases only

B.

vacuum

C.

liquids and gases only

D.

solids, liquids and gases

SOLUTION

Solution : D

A mechanical wave requires medium to propagate. Hence, it is not capable of transmitting its energy through vacuum.

A sound wave is an example of mechanical wave. It can propagate through all the three mediums solids, liquids and gases. However, it is incapable of travelling through vacuum.

Question 3

Very loud music can be considered as noise.

A.

True

B.

False

SOLUTION

Solution : A

Very loud music causes discomfort and can damage the ears. Hence, it can be considered as noise.

Question 4

The function of the three small bones in middle ear is to:

A. Protect the ear
B. Enhance the vibrations reaching middle ear
C. Produce sound inside the ear
D. Produce hormones essential for hearing

SOLUTION

Solution : B

There are three bones present in the middle ear - malleus, incus and stapes. The function of these bones is to amplify the vibrations that reach the middle ear and send them to the inner ear.

Question 5

What is the speed of sound in vacuum?

A. 330 ms−1
B. 3×108 ms−1
C. 0 ms−1
D. 250 ms−1

SOLUTION

Solution : C

Sound wave is a mechanical wave which requires a medium for its propagation. It cannot travel through vacuum. Hence, the speed of sound is zero in vacuum.

Question 6

The ____ of a sound wave is expressed in hertz (Hz).

A.

frequency

B.

amplitude

C. wavelength
D. time period

SOLUTION

Solution : A

The frequency of a sound wave is expressed in hertz (Hz). Amplitude and wavelength are measured in metre (m). Time period is measured in second (s).

Question 7

We must never put sharp, pointed objects into our ears as the eardrum can get damaged.

A.

True

B.

False

SOLUTION

Solution : A

The given statement is true. We must never put sharp, pointed objects such as pen, pencil, etc. into our ears. It can damage the eardrum and cause hearing impairment since the eardrum is a thin, stretched membrane.

Question 8

Which of the following frequency ranges are audible to us?

A. 20-200 Hz
B. 200-2000 Hz
C. 2000-20,000 Hz
D. 0-20 Hz

SOLUTION

Solution : A, B, and C

The standard range of audible frequencies for humans is 20 to 20,000 Hz. As we can see, except 0-20 Hz, all other options lie in the audible range.

Question 9

The time taken for 10 oscillations is 1 s. The frequency of the wave is:

A.

10 Hz

B.

110 Hz

C.

20 Hz

D.

120 Hz

SOLUTION

Solution : A

Here, total number of oscillations = 10
Total time taken = 1 s
Hence, time taken for 1 oscillation = 110 s

The time required to complete one oscillation is known as time period (T).

Now, frequency, f=1T = 10 Hz

Question 10

Vocal cords are present in ___.

A.

oesophagus

B.

larynx

C.

ear drum

D.

pharynx

SOLUTION

Solution : B

Vocal cords are present in the larynx. It is also called as voice box. Their vibration is responsible for the production of sound in humans.

Related Exams