# An observer moves towards a stationary source of sound, with a velocity one­fifth of the velocity of sound. What is the percentage increase in the apparent frequency ? Option 1) 5% Option 2) 20% Option 3) 0 Option 4) 0.5%

As we learnt in

Doppler Effect -

When a source of sound and a listener are in motion relative to each other, the frequency of the sound heard by the listener is not the same as the source frequency.

-

By Doppler's effect

$\frac{{\upsilon }'}{\upsilon }= \frac{\nu _{s}+\nu _{0}}{\nu _{s}}$ (where is the velocity of sound)

Correct option is 2.

Option 1)

5%

This is an incorrect option.

Option 2)

20%

This is the correct option.

Option 3)

0

This is an incorrect option.

Option 4)

0.5%

This is an incorrect option.

### Preparation Products

##### Knockout JEE Main April 2021 (One Month)

Personalized AI Tutor and Adaptive Time Table, Self Study Material, Weekend Live Classes, Mentorship from our Experts, Unlimited Mock Tests and Personalized Analysis Reports, 24x7 Doubt Chat Support,.

₹ 14000/- ₹ 4999/-
##### Knockout JEE Main May 2021

Personalized AI Tutor and Adaptive Time Table, Self Study Material, Weekend Live Classes, Mentorship from our Experts, Unlimited Mock Tests and Personalized Analysis Reports, 24x7 Doubt Chat Support,.

₹ 22999/- ₹ 9999/-
##### Test Series JEE Main May 2021

Unlimited Chapter Wise Tests, Unlimited Subject Wise Tests, Unlimited Full Mock Tests, Get Personalized Performance Analysis Report,.

₹ 6999/- ₹ 2999/-
##### Knockout JEE Main May 2022

Personalized AI Tutor and Adaptive Time Table, Self Study Material, Weekend Live Classes, Mentorship from our Experts, Unlimited Mock Tests and Personalized Analysis Reports, 24x7 Doubt Chat Support,.

₹ 34999/- ₹ 14999/-