Q. A source is moving towards an observer with a speed of $20\ m/s$ and having frequency of $240\ Hz.$ The observer is now moving towards the source with a speed of $20\ m/s.$ Apparent frequency herad by observer, if velocity of sound is $340\ m/s,$ is
A) $240\ Hz$
B) $270\ Hz$
C) $280\ Hz$
D) $360\ Hz$
Explanation
(b) $n^{'} = n\left( \frac{v + v_{O}}{v - v_{S}} \right) = 240\left( \frac{340 + 20}{340 - 20} \right) = 270\ Hz$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.