Q. A vehicle with a horn of frequency $n$is moving with a velocity of $30ms^{- 1}$ in a direction perpendicular to the straight line joining the observer and the vehicle. The observer perceives the sound to have a frequency $(n + n_{1})$.If the sound velocity in air is $300ms^{- 1}$, then
A) $n_{1} = 10n$
B) $n_{1} = 0$
C) $n_{1} = 0.1n$
D) $n_{1} = - 0.1n$
Explanation
(b) As the source is moving perpendicular to straight line joining the observer and source, (as if moving along a circle), apparent frequency is not affected $n_{1} = 0$.
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.