Question

An observer is moving with speed v, towards a
stationary source emitting a sound wave of
wavelength 2. The change in wavelength detected
by the observer is (v = speed of sound)
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(2) avo
loloy
(4) Zero
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Answer 1

Answer:

2 is the write answer

hope it helps

Answer 2

The change in wavelength detected by the observer is $\frac{2v }{343}$.

Explanation:

Given:

       Speed of the observer = v

       initial wavelength of stationary source emitting sound wave = 2 m

            So,    λ = 2 m

       We need to find the change in wavelength. So, for that

                  Doppler Shift for sound equation.

 New wavelength is λ'.

                       ⇒ λ' = $\frac{ (c + v)}{c}$

We know that speed of sound c = 343 m/s.

                      ⇒ λ' = $\frac{ 2 (343 + v)}{343}$

Hence, change in wavelength,

                           ⇒ λ' - λ = $\frac{ 2v}{343}$