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# Test: Characteristics Of Sound Waves

## 20 Questions MCQ Test Science Class 9 | Test: Characteristics Of Sound Waves

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This mock test of Test: Characteristics Of Sound Waves for Class 9 helps you for every Class 9 entrance exam. This contains 20 Multiple Choice Questions for Class 9 Test: Characteristics Of Sound Waves (mcq) to study with solutions a complete question bank. The solved questions answers in this Test: Characteristics Of Sound Waves quiz give you a good mix of easy questions and tough questions. Class 9 students definitely take this Test: Characteristics Of Sound Waves exercise for a better result in the exam. You can find other Test: Characteristics Of Sound Waves extra questions, long questions & short questions for Class 9 on EduRev as well by searching above.
QUESTION: 1

### Which of the following correctly relates the wavelength λ, frequency f and velocity v of sound?​

Solution:

We know that, T = 1 / f
Where, f is the frequency, T is time period
Also, Speed  =  Distance / Time taken
Speed of wave is it's velocity v, and Distance of wave is it's wavelength lemda.
Substituting these into the equation.
=>  v = lemda / T
=>    v  = lemda  f
As,  T =  1/ f
Therefore,  v = f lemda

QUESTION: 2

### The wavelength of the sound produced by a tuning fork of frequency 450 Hz which is set to vibrate in the air (take the velocity of sound in air as 320 m/s) is

Solution:

Wavelength = speed of air (v) / frequency (ν)

Wavelength = 320/ 450= 0.711 m

QUESTION: 3

### A siren has 16 holes and is making 960 revolutions per minute. The frequency of the sound produced by the siren is:

Solution:

Number of holes h = 16
Revolutions per minute = 960

Revolutions per second =960/60 =16

frequency = no. of holes x revolutions per sec

= 16 x16 =256 Hz

QUESTION: 4

SI unit of frequency is

Solution:

The  hertz (symbol Hz) is the SI unit of frequency defined as the number of cycles per second of a periodic phenomenon.

This unit is named after a German physicist Heinrich Hertz.

QUESTION: 5

Arrange in increasing order – Speed of sound in steel, in distilled water, in sea water and in oxygen.

Solution:

The speed of sound decreases as we go from solid to gaseous state because the density of particles decreases from solid to gaseous.

QUESTION: 6

A top makes 16 rotations about its own axis within 0.4 seconds, its frequency is:

Solution:

In 0.4 sec=16 rotations,

so in, 1 sec = 16/0.4

=160/4

=40 rotations

QUESTION: 7

On which quantity does the pitch of the sound depend?

Solution:

The pitch of sound depends on the frequency of vibration. The higher the frequency the more shrill is the sound and vice versa.

QUESTION: 8

What is the difference between a low pitched and high pitched sound?

Solution:

High pitch sound is a sound which has a high frequency. usually shrill sounds have a high pitch. for ex. a whistle has high pitch.

low pitch sounds are sounds which have low frequency rate. for ex. horse voice.

loud sounds have a high amplitude. for ex. a mega phone gives sound of high amplitude.

soft sounds are sounds which have low amplitude. for ex. a birds chirping has low amplitude.

QUESTION: 9

A compression is a region of

Solution:

Compression is the region of high pressure and rarefaction is the region of low pressure. Higher the pressure in a region, higher is the number of particles per unit volume and hence higher is the density of the medium. So, a sound wave propagates through a medium as the variation in its pressure or density.

QUESTION: 10

Sound from a flute and sound from a harmonica played by passing air through musical instrument, at same time and same distance from ear and traveling through same medium air, they differ in sounds due to difference in

Solution:

Pitch of sound is how brain interprets the frequency of the emitted sound. In harmonica, vibration of particles is more at the source, and hence more frequency. Therefore, it has higher pitch. Thus, harmonica sound appears different than sound of flute

QUESTION: 11

A stationary rail engine produces whistle with a frequency 2600 Hz. A person standing at a distance of 550 m from engine will listen ___________ no. of waves within one minute.​

Solution:
QUESTION: 12

If we increase the temperature of air from 0°C to 22°C, then the speed of sound would

Solution:

When the temperature increases then the kinetic energy of the particles also increases as a result they move more faster and so the energy is more fastly transferred through the molecules of the medium.

QUESTION: 13

Compressions are the regions where

Solution:

A compression is a region in a longitudinal wave where the particles are closest together. A rarefaction is a region in a longitudinal wave where the particles are furthest apart.

QUESTION: 14

By counting the number of vibrations of a tuning fork per second, __________ can be found.

Solution:
QUESTION: 15

A bell vibrates 600 times within 3/2 seconds, its frequency and time period will be:

Solution: QUESTION: 16

A swing has a time period of 1.4 seconds. The no. of oscillations made by it within 1 minute 24 seconds will be:​

Solution:

Oscillation  = time / time period
⇒ 84 second / 1.4 second
⇒ 60

QUESTION: 17

Choose one of the following, on which the frequency of a vibrating body does not depend.

Solution:

When waves travel from one medium to another the frequency never changes. As waves travel into the denser medium, they slow down & wavelength decreases. Part of the wave travels faster for longer causing the wave to turn. The wave is slower but the wavelength is shorter means frequency remains the same.

QUESTION: 18

A baby cries with a frequency 712 Hz, if the speed of sound in air is 356m/s, the wavelength of sound is:

Solution: QUESTION: 19

A progressive transverse wave has a speed of 5040 m/s, its frequency is 315 Hz, then the distance between a crest and an immediate trough is:

Solution: QUESTION: 20

Sound of single frequency is called

Solution:

The only sound which consists of a single frequency is the pure SINE TONE such as produced by a sine wave OSCILLATOR or approximated by a tuning fork. All other sounds are complex, consisting of a number of frequencies of greater or lesser intensity. The frequency content of a sound is its SPECTRUM.