Q. The frequency of a whistle of an engine is $600\ cycles/sec$ is moving with the speed of $30\ m/sec$ towards an observer. The apparent frequency will be (velocity of sound $= 330\ m/s$)
A) $600\ cps$
B) $660\ cps$
C) $990\ cps$
D) $330\ cps$
Explanation
(b) $n^{'} = n\left( \frac{v}{v - v_{S}} \right) = 600\left( \frac{330}{300} \right) = 660\ cps$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.