wave_mechanics dopplers_effect Question 42

Question: A source of sound of frequency 90 vibrations/ sec is approaching a stationary observer with a speed equal to 1/10 the speed of sound. What will be the frequency heard by the observer

[MP PMT 2000]

Options:

A) 80 vibrations/sec

B) 90 vibrations/sec

C) 100 vibrations/sec

D) 120 vibrations/sec

Show Answer

Answer:

Correct Answer: C

Solution:

$ n’=n( \frac{v}{v-v _{s}} )=90( \frac{v}{v-\frac{v}{10}} ) $ = $ 100\frac{Vibration}{\sec } $