Home
Class 11
PHYSICS
A train whistling at constant frequency ...

A train whistling at constant frequency is moving towards a station at a constant speed V. The train goes past a stationary observer on the station. The frequency `n^(')` of the sound as heard by the observer is plotted as a function of time t, figure. Identify the expected curve.

A

B

C

D

Text Solution

Verified by Experts

The correct Answer is:
C
Let th original frequency of the source is `n_(0)`.
Let the speed of sound wave in the medium is v.
As observer is stationary

Apparent frequecny `n_(a)=((v)/(v-v_(s)))n_(0)" "` [when train is approaching]
`" " =((v)/(v-v_(s)))n_(0)=n_(a)gt n_(0)`
When the train is going away from the observer
Apparent frquency `n_(a)=((v)/(v+v_(s)))n_(0)=n_(a)ltn_(0)`
Hence, the expected curve is (c).
Promotional Banner

Topper's Solved these Questions

  • WAVES

    NCERT EXEMPLAR ENGLISH|Exercise MULTIPLE CHOICE QUESTIONS (MORE THAN ONE OPTIONS )|7 Videos

  • WAVES

    NCERT EXEMPLAR ENGLISH|Exercise VERY SHORT ANSWER TYPE QUESTIONS|7 Videos

  • UNITS AND MEASUREMENTS

    NCERT EXEMPLAR ENGLISH|Exercise Long Answer Type Questions|9 Videos

  • WORK, ENERGY AND POWER

    NCERT EXEMPLAR ENGLISH|Exercise Long answer|1 Videos

Similar Questions

Explore conceptually related problems

A train is moving towards a stationary observer. Which of the following curve best represents the frequency recived by observer f as a function of time?

A source of sound is travelling towards a stationary observer. The frequency of sound heard by the observer is 25% more that the actual frequency. If the speed of sound is v, that of the source is

A source of sound emitting a note of constant frequency is moving towards a stationary listener and then recedes from the listener with constant velocity maintained throughout the motion. The frequency heard by the listener (f). when plotted against time (t) will give the following curve(s).

a bus is moving towards and stationary observer with speed 20 m/s blows a horn of frequency 200 Hz. the frequency of sound heard by the observer is approximately ( take speed of sound 320 m/s)

A train is moving with a constant speed along a circular track. The engine of the train emits a sound of frequency f. The frequency heard by the guard at the rear end of the train.

A train standing at the outer signal of a railway station blows a whistle of frequency 400 Hz in still air. The train begins to move with a speed of 30 m s^(- 1) towards the platform. The frequency of the sound heard by an observer standing on the platform is (Speed of sound in air = 330 m s^(-1) )

The engine of a train sound a whistle at frequency v, the frequency heard by a passenger is

The engine of a train sound a whistle at frequency v , the frequency heard by a passenger is

A sound source is moving towards a stationary observer with 1/10 of the speed of sound. The ratio of apparent to real frequency is

A source of frequency 'f' is stationary and an obsercer starts moving towards it at t=0 with constant small acceleration. Then the variation of observed frequency 'f' registered by the observer with time is best represented as