Sound Test

Result

Sound Test - 6

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Weekly Quiz Competition

Question 1
1 / -0

Pitch of a voice refers to the

A
quality of sound

B
frequency of sound

C
intensity of sound

D
chord of sound
Question 2
1 / -0

If two men talk on the moon's surface,

A
they hear each other with lower frequency.

B
they hear each other with higher frequency.

C
they can only hear each other.

D
they can't hear each other.

Solution

Correct answer - 4
Sound cannot travel through the vacuum or space.
Question 3
1 / -0

On which of the following phenomena do bats rely the most to find their way in the dark?

A
Bats have a very high pressure sensitivity in their skin, which can differentiate the pressure differences when they are flying about.

B
Bats have the best night vision of all the nocturnal animals and can see even in the absence of any ambient light.

C
Bats use a system akin to SONAR in which they are guided by ultrasonic waves which they produce.

D
Bats employ thermal imaging very well.

Solution

Bats can fly in the dark without hitting obstacles because they are guided by the ultrasonic waves which they produce.
Question 4
1 / -0

What are ultrasonic waves?

A
Sound waves having frequency less than the audio frequency range.

B
Sound waves produced in vacuum.

C
Sound waves having frequency higher than audio frequency range.

D
None of these.

Solution

Correct answer - 3
Ultrasound is an acoustic (sound) energy in the form of waves having a frequency above the human hearing range. The highest frequency that the human ear can detect is approximately 20 thousand cycles per second (20,000 Hz). This is where the sonic range ends, and where the ultrasonic range begins.
Question 5
1 / -0

The velocity of sound in air at 0^oC is

A
332 m/s

B
1500 m/s

C
2500 m/s

D
5000 m/s
Question 6
1 / -0

Which of the following statements is wrong?

A
Velocity of light in vacuum is 3 x 10⁸ m/s.

B
Sound travels faster in dry air than in the moist air.

C
The audible frequency range for human being is 20 Hz - 20000 Hz.

D
Sound waves do not propagate in vacuum.
Question 7
1 / -0

The distance between two successive crests or trough is 1 m, and the velocity of the waves is 320 m/s. Find out the frequency.

A
320 Hz

B
430 Hz

C
306 Hz

D
400 Hz
Question 8
1 / -0

A body is vibrating 6,000 times in one minute. If the velocity of sound in air is 360 m/s, find the wavelength of waves produced.

A
100 m

B
3.6 m

C
16.6 m

D
none of these

Solution

Correct answer - 2
Frequency = Number of vibrations per second
Now, if a body is vibrating 6000 times per minute, it will vibrate 6000/60 times per second.
So, its frequency will be = 6000/60 = 100 Hz
Now, the wavelength is given as the ratio of speed and frequency.
Here, speed = 360 m/s
So,
Wavelength = 360 / 100
Wavelength = 3.6 m
Question 9
1 / -0

If the period of small ripples in water is 0.1 s, and their wavelength is 5 cm, what is the speed of the wave?

A
50 cms^–1

B
5 cms^–1

C
0.5 cms^–1

D
none of these

Solution

Speed of the wave is given by

v = Here, λ is the wavelength and T is the period.

Hence
Question 10
1 / -0

Waves of frequency 100 Hz are produced in a string as shown below. What will be the velocity of the wave?

A
20 ms^-1

B
5 cms^-1

C
2000 ms^-1

D
2 cms^-1

Solution

Correct answer - 1
Velocity = Frequency × Wavelength = 100 × = 20 m/s
Question 11
1 / -0

Two sound waves in the air have their wavelength in the ratio 2:5. The ratio of their frequency is

A
2 : 5

B
5 : 2

C
10 : 1

D
none of these
Question 12
1 / -0

Study the following graphs to identify the statement that is correct.

A
Wave B has a higher pitch than wave A.

B
Waves B and A have the same pitch.

C
Wave A has a higher pitch than wave B.

D
None of these

Solution

The pitch of a sound wave is directly propotional to the frequency of the wave, i.e. the higher the frequency, the higher will be its pitch. In this case, wave A has higher frequency than wave B. Therefore, wave A has a higher pitch than wave B.
Question 13
1 / -0

A person who is standing between two cliffs shouts and hears the first two echoes after 4 s and 6 s, respectively. What is the distance between the cliffs if the velocity of sound is 320 m/s?

A
640 m

B
960 m

C
1600 m

D
1000 m

Solution

Using the formula v = 2d/t,

320 = 2d₁/4
d₁= 640 m
320 = 2d₂/6
d₂ = 960 m
Total distance = 1600 m
Question 14
1 / -0

Normal conversation has intensity of about

A
20 dB

B
65 dB

C
120 dB

D
10 dB
Question 15
1 / -0

The intensity I of sound waves at a point from the vibrating body varies with distance as

A
I α d

B
I α

C
I α

D
I α d²
Question 16
1 / -0

A source of wave produces 40 crests and 40 troughs in 0.6 seconds.

The frequency of the wave is

A
100 Hz

B
40 Hz

C
333 Hz

D
67 Hz

Solution

Number of crests and troughs in one cycle is 1 each.
Frequency = Number of crests/Time
Number of crests = 40, Time = 0.6 sec
Question 17
1 / -0

If the frequency of a tuning fork is 200 Hz and the velocity of sound in air is 320 m/s, the distance travelled by the sound while the fork completes 10 vibrations, is

A
16 m

B
18 m

C
20 m

D
22 m
Question 18
1 / -0

Waves formed over water surface are

A
longitudinal

B
transverse

C
both transverse and longitudinal

D
neither transverse nor longitudinal
Question 19
1 / -0

The time period of Khushi`s voice is 0.002 sec. Frequency of her voice is

A
5000 Hz

B
500 Hz

C
50 Hz

D
5 Hz
Question 20
1 / -0

Frequency of vibration of a sitar is 200 Hz. The time period is

A
0.005 s

B
50 s

C
500 s

D
200 s