When a string is divided into three segments of lengths l 1 , l 2 and l 3 the fundamental frequencies of these three segments are ν 1 , ν 2 and ν 3 respectively. The original fundamental frequency ν of the string is

1 ν = 1 ν 1 + 1 ν 2 + 1 ν 3

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A train moving at a speed of $220 {ms}^{- 1}$ towards a stationary object, emits a sound of frequency $1000 Hz$ . Some of the sound reaching the object gets reflected back to the train as echo. The frequency of the echo as detected by the driver of the train is:
(speed of sound in air is $330 {ms}^{- 1}$ )

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Important Questions on Waves

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Gamma Question Bank for Medical Physics>Chapter 15 - Waves>Assignment>Q 39

A train moving at a speed of

220 {ms}^{- 1}

towards a stationary object, emits a sound of frequency

1000 Hz

. Some of the sound reaching the object gets reflected back to the train as echo. The frequency of the echo as detected by the driver of the train is:
(speed of sound in air is

330 {ms}^{- 1}

)

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Gamma Question Bank for Medical Physics>Chapter 15 - Waves>Assignment>Q 40

A source of frequency

v

gives

5

beats/second when sounded with a source of frequency

200 Hz .

The second harmonic of frequency

2 v

of source gives

10

beats/second when sounded with a source of frequency

420 Hz .

The value of

v

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Gamma Question Bank for Medical Physics>Chapter 15 - Waves>Assignment>Q 41

A vibrating tuning fork is moving slowly and uniformly in a horizontal circular path of radius

8 m .

The shortest distance of an observer in same plane from the tuning fork is

9 m .

The distance between the tuning fork and observer at the instant when apparent frequency becomes maximum is

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Gamma Question Bank for Medical Physics>Chapter 15 - Waves>Assignment>Q 42

The frequency changes by

10 %

as a sound source approaches a stationary observer with constant speed

V_{s} .

What would be percentage change in the frequency as the source recedes the observer with same speed

(V_{s} < V) ?

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Gamma Question Bank for Medical Physics>Chapter 15 - Waves>Assignment>Q 43

A train blowing its whistle moves with constant speed on a straight track towards observer and then crosses him. If the ratio of difference between the actual and apparent frequencies be

3 : 2

in the two cases, then the speed of train is [

v

is speed of sound]

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Gamma Question Bank for Medical Physics>Chapter 15 - Waves>Assignment>Q 44

A man is standing on a railway platform listening to the whistle of an engine that passes the man at constant speed without stopping. If the engine passes the man at time instant

t_{0},

how does the frequency

f

of the whistle as heard by the man changes with time?

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Gamma Question Bank for Medical Physics>Chapter 15 - Waves>Assignment>Q 45

A whistle $' S'$ of frequency $f$ revolves in a circle of radius $R$ at a constant speed $v .$ What is the ratio of maximum and minimum frequency detected by a detector $D$ at rest at a distance $2 R$ from the center of circle as shown in figure? (take $' c'$ as speed of sound)
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Gamma Question Bank for Medical Physics>Chapter 15 - Waves>Assignment>Q 1

In a guitar, two strings

A

and

B

made of same material are slightly out of tune and produce beats of frequency

6 Hz

. When tension in

B

is slightly decreased, the beat frequency increases to

7 Hz

. If the frequency of

A

530 Hz

, the original frequency of

B

will be:

A train moving at a speed of 220ms-1 towards a stationary object, emits a sound of frequency 1000Hz. Some of the sound reaching the object gets reflected back to the train as echo. The frequency of the echo as detected by the driver of the train is: (speed of sound in air is 330ms-1)

Important Questions on Waves

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