A tuning fork arrangement (pair) produces `4 beats//sec` with one fork of frequrncy `288cps`. A little wax is placed on the unknown fork and it then produces `2 beats//sec`. The frequency of the unknown fork is

Options

A. (a) `286 cps`
B. (b) `292 cps`
C. ( c ) `294 cps`
D. (d) `288 cps`

Answer

B

Explanation

(b) A tuning fork produces `4 beats//sec` with another tuning fork of frequency `288 cps`. From this information we can conclude that the frequency of unknown fprk is `288 + 4 cps` or `288 - 4 cps` i.e. `292 cps` or `284 cps`. When a little wax is placed on the unknown fork, it produces `2beats//sec`. when a little wax is placed on the unknown fork, its frequency decreases and simultaneously the beat frequency decreases confirming that the frequency of the unknown fork is `292 cps`.