A tuning fork arrangement (pair) produces `4 beats//sec` with one fork of frequency `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. 286 cps
B. 292 cps
C. 294 cps
D. 288 cps

Answer

B

Explanation

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 fork 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 `2 beats//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.