Question

Two tuning fork a and b give 4 beats per second when sounded together. The frequency of a is 320 hz. When some wax is added to b and it is sounded with a, 4 beats per second are again heard. The frequency of b is

Answer 1

With the wax the frequency of A is 384 + 4 = 388 Hz

Without the wax the frequency of A is 390 Hz. (384+6)

Since adding mass lowers the frequency we know that A was 390 Hz instead of 378Hz, because lowering the frequency of 378 Hz would cause MORE beats to be heard.

A beat per second is equivalent to a cycle per second. ie ) The number of beats per second is equal to the difference in frequency.