Question

The wave length of the sound produced by a
source is 0.8m. If the source moves towards the
stationary listener at 32 m/s, what is the apparent
wave length of sound if the velocity of sound is 320m/s
1) 0.32 m
2) 0.4 m
3) 0.72 m
4) 0.80 m
​

Answer 1

Option 4 ) 0.08 m ........

Answer 2

Given that,

Wavelength of sound produced by a source is, $\lambda=0.8\ m$

Speed of source, $v_s=32\ m/s$

The velocity of sound, v = 320 m/s

To find,

The apparent  wave length of sound.

Solution,

When the source of wavelength $\lambda$ approaches the stationary observer, then the apparent  wavelength of sound is given by using Doppler's effect as :

$\lambda'=\lambda(\dfrac{v-v_s}{v})\\\\\lambda'=0.8\times (\dfrac{320-32}{320})\\\\\lambda'=0.72\ m$

So, the apparent  wavelength of sound is 0.72 meters. Hence, the correct option is (3).

Learn more,

Doppler's effect

https://brainly.in/question/14313444