Question

A source emits waves of wavelength 60cm . This source is moving towards north with a speed of 1/5th of the speed of the sound . The apparent wavelength of the wave in the north and south direction of the moving source will be?

Answer 1

Wavelength =50 cm

velocity =v

Source velocity =v/5

Apparent wavelength =[50*(v-v/5)/v]

Apparent wavelength =40 cm

Answer 2

The apparent wavelength in the North will be 48cm, while in South will be 72cm.

Wavelength of the waves = 60cm (Given)

Speed of the wave = 1/5 sound  (Given)

Apparent wavelength in the north will be -

λ' = λ (v−vs/v) where vs represents the velocity of the source

= 330/5

= 66m/s

Therefore,

λ' = 60(330−66/330)

= 48 cm

Apparent wavelength in the south will be -

λ' = λ(v+vs/v)

λ' = 60(330+66/330)

= 72 cm