Question

A tuning fork A produces 4 beats s-1 with another tuning fork B of frequency 320 Hz. On filing one of the

prongs of A 4 beats s_1 are again heard when sounded with the same fork B. Then, the frequency of the fork A before filing is?

Answer 1

The frequency of tuning fork A is 324 Hz.

Explanation :

Both the tuning fork produce 4 beats/sec

=> Fa ± Fb = 4

=> Fa ± 320 = 4

=> Fa = 316 or 324

But we know that on filing a tuning fork, its frequency decreases.

So if initially it would have been 316 Hz than after filing it will reduce further and can never be able to produce 4 beats/sec

But if it was initially as 324 Hz then after filing it will become 316 Hz so as to produce again 4 beats/sec with B

Hence the frequency of tuning fork A is 324 Hz.