A source of sound emitting a note of frequency 200 Hz moves towards an observer with a velocity v equal to the velocity of sound. If the observer also moves away from the source with the same velocity v, the apparent frequency heard by the observer is 

(1) 50 Hz

(2) 100 Hz

(3) 150 Hz

(4) 200 Hz

A source of sound is traveling towards a stationary observer. The frequency of the sound heard by the observer is three times the original frequency. The velocity of sound is v m/sec. The speed of the source will be :

(1) $\frac{2}{3}v$

(2) v

(3) $\frac{3}{2}v$

(4) 3v

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 : 

(1) 10/9

(2) 11/10

(3) (11/10)²

(4) (9/10)²

The speed of sound in air at a given temperature is 350 m/s. An engine blows whistle at a frequency of 1200 cps. It is approaching the observer with velocity 50 m/s. The apparent frequency in cps heard by the observer will be :

(1) 600

(2) 1050

(3) 1400

(4) 2400

The Doppler's effect is applicable for :

(1) Light waves

(2) Sound waves

(3) Space waves

(4) Both (1) and (2)

A source of sound is moving with constant velocity of 20 m/s emitting a note of frequency 1000 Hz. The ratio of frequencies observed by a stationary observer while the source is approaching him and after it crosses him will be

(1) 9 : 8

(2) 8 : 9

(3) 1 : 1

(4) 9 : 10

(Speed of sound v = 340 m/s)

A source and listener are both moving towards each other at a speed of v/10, where v is the speed of sound. If the frequency of the note emitted by the source is f, the frequency heard by the listener would be nearly :
1. 1.11 f
2. 1.22 f
3. f
4. 1.27 f

A motor car blowing a horn of frequency 124vib/sec moves with a velocity 72 km/hr towards a tall wall. The frequency of the reflected sound heard by the driver will be (velocity of sound in air is 330 m/s) 

(1) 109 vib/sec

(2) 132 vib/sec

(3) 140 vib/sec

(4) 248 vib/sec

A source of sound of frequency n is moving towards a stationary observer with a speed S. If the speed of sound in air is V and the frequency heard by the observer is n₁, the value of n₁/n is 

(1) (V + S)/V

(2) V/(V + S)

(3) (V – S)/V

(4) V/(V – S)

An observer is moving away from the source of the sound of frequency 100 Hz. His speed is 33 m/s. If the speed of sound is 330 m/s, then the observed frequency is :

(1) 90 Hz

(2) 100 Hz

(3) 91 Hz

(4) 110 Hz