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An observer moves towards a stationary source of sound with a speed l/5th of the speed of sound. The wavelength and frequency of the source emitted by any source be λ, and  f respectively. The apparent frequency and wavelength recorded by the observer are respectively -
  • a)
    0.8f, 0.8λ  
  • b)
    1.2f, l.2λ
  • c)
    1.2f, λ    
  • d)
    f, 1.2X
Correct answer is option 'C'. Can you explain this answer?
Verified Answer
An observer moves towards a stationary sourceof sound with a speed l/5...

wavelength remains constant (unchanged) in this case.
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Most Upvoted Answer
An observer moves towards a stationary sourceof sound with a speed l/5...
Let's assume the speed of sound is "v" and the wavelength of the source emitted by any source is "λ".

Since the observer is moving towards the stationary source with a speed of "v/5", the relative velocity between the observer and the source is (v - v/5) = (4v/5).

The formula for the Doppler effect in sound is given by:

f' = (v + Vo) / (v + Vs) * f

where:
f' = frequency observed by the observer
f = frequency emitted by the source
Vo = velocity of the observer
Vs = velocity of the source

In this case, the observer is moving towards the source, so Vo = (4v/5) and Vs = 0 (since the source is stationary).

Plugging in the known values into the formula, we get:

f' = (v + 4v/5) / (v + 0) * f
f' = (5v/5 + 4v/5) / (v + 0) * f
f' = (9v/5) / v * f
f' = (9/5) * f

So, the frequency observed by the observer is (9/5) times the frequency emitted by the source.

Now, let's calculate the wavelength observed by the observer.

The formula for calculating wavelength is given by:

λ' = λ * (v + Vo) / (v + Vs)

Plugging in the known values:

λ' = λ * (v + 4v/5) / (v + 0)
λ' = λ * (9v/5) / v
λ' = (9/5) * λ

So, the wavelength observed by the observer is also (9/5) times the wavelength emitted by the source.

In summary, the wavelength and frequency of the source emitted by any source will both be multiplied by a factor of 9/5 when observed by an observer moving towards the stationary source with a speed of v/5.
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An observer moves towards a stationary sourceof sound with a speed l/5th of the speed of sound. The wavelength and frequency of thesource emitted by any source be λ, and f respectively. The apparent frequency and wavelength recorded by the observer arerespectively -a)0.8f, 0.8λb)1.2f, l.2λc)1.2f, λ d)f, 1.2XCorrect answer is option 'C'. Can you explain this answer?
Question Description
An observer moves towards a stationary sourceof sound with a speed l/5th of the speed of sound. The wavelength and frequency of thesource emitted by any source be λ, and f respectively. The apparent frequency and wavelength recorded by the observer arerespectively -a)0.8f, 0.8λb)1.2f, l.2λc)1.2f, λ d)f, 1.2XCorrect answer is option 'C'. Can you explain this answer? for NEET 2024 is part of NEET preparation. The Question and answers have been prepared according to the NEET exam syllabus. Information about An observer moves towards a stationary sourceof sound with a speed l/5th of the speed of sound. The wavelength and frequency of thesource emitted by any source be λ, and f respectively. The apparent frequency and wavelength recorded by the observer arerespectively -a)0.8f, 0.8λb)1.2f, l.2λc)1.2f, λ d)f, 1.2XCorrect answer is option 'C'. Can you explain this answer? covers all topics & solutions for NEET 2024 Exam. Find important definitions, questions, meanings, examples, exercises and tests below for An observer moves towards a stationary sourceof sound with a speed l/5th of the speed of sound. The wavelength and frequency of thesource emitted by any source be λ, and f respectively. The apparent frequency and wavelength recorded by the observer arerespectively -a)0.8f, 0.8λb)1.2f, l.2λc)1.2f, λ d)f, 1.2XCorrect answer is option 'C'. Can you explain this answer?.
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