Q. A source and an observer approach each other with same velocity $50\ m/s.$ If the apparent frequency is $435s{ec}^{- 1}$, then the real frequency is
A) $320\ s^{- 1}$
B) $360s{ec}^{- 1}$
C) $390s{ec}^{- 1}$
D) $420s{ec}^{- 1}$
Explanation
(a) $n^{'} = n\left\lbrack \frac{v + v_{O}}{v - v_{S}} \right\rbrack;$
Here $v = 332m/s$and $v_{O} = v_{s} = 50\ m/s$
$\Rightarrow 435 = n\left\lbrack \frac{332 + 50}{332 - 50} \right\rbrack \Rightarrow n = 321.12\ \sec^{- 1} = 320\ \sec^{1}$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.