A sound wave of frequency f travels horizontally to the right. It is reflected from a large vertical plane surface moving to the left with a speed v. The speed of sound in the medium is c, then

see full answer

Your Exam Success, Personally Taken Care Of

1:1 expert mentors customize learning to your strength and weaknesses – so you score higher in school , IIT JEE and NEET entrance exams.

An Intiative by Sri Chaitanya

The frequency of the reflected wave is $\frac{f (c + v)}{c - v}$

The number of beats heard by a stationary listener to the left of the reflecting surface is $\frac{f v}{c - v}$ .

The number of waves striking the surface per second is $\frac{f (c + v)}{c}$

The wavelength of the reflected wave is $\frac{c (c - v)}{f (c + v)}$

answer is A, B, C.

(Unlock A.I Detailed Solution for FREE)

Best Courses for You

JEE

NEET

Foundation JEE

Foundation NEET

CBSE

Detailed Solution

Moving plane is like a moving observer.
Therefore, number of waves encountered by moving plane.
$f_{1} = f (\frac{v + v_{0}}{v}) = f (\frac{c + v}{c})$
Frequency of reflected wave,
$f_{2} = f_{1} (\frac{v}{v - v_{s}}) = f (\frac{c + v}{c - v})$
Wavelength of reflected wave
$λ_{2} = \frac{v}{f_{2}} = \frac{c}{f_{2}} = \frac{c}{f} (\frac{c - v}{c + v})$
Number of beats heard = $f_{2} - f = \frac{2 v f}{c - v}$