A source of sound having frequency $100$ Hz is rotating in a circle of radius $2$ m with a speed of $30$ m/s. The frequency detected by an observer at the centre of circle is? [Take speed of sound in air as $330$ m/s]

900

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1000

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1100

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1200

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Solution

The correct option is B $900$ Hz
The number of complete waves or cycles produced in one second is called frequency of the wave.
The number of vibrations per second is also called frequency.
SI unit of frequency in hertz (Hz).
$1 h e r t z$ is equal to $1 v i b r a t i o n p e r s e c o n d .$
Solution:
The frequency of $100 h e r t z$ means that the source of sound vibrates $100 t i m e s i n 1 s e c o n d$ .
$[1 m i n = 60 s e c]$
Number of vibrations in 1 second $= 100$
Number of Vibrations in 60 Second( 1min) $= 100 \times 60 = 6000$
Hence, the source of sound vibrates $6000 t i m e s$ in a minute.

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A source of sound having frequency 100Hz is rotating in a circle of radius 2m with a speed of 30 m/s. The frequency detected by an observer at the centre of circle is? [Take speed of sound in air as 330 m/s]

A source of sound having frequency $100$ Hz is rotating in a circle of radius $2$ m with a speed of $30$ m/s. The frequency detected by an observer at the centre of circle is? [Take speed of sound in air as $330$ m/s]