Question

Two tuning forks, A and B , give beats/s when sound together. The frequency of A is 320 Hz. When some wax is added to B and sounded with fork A , 4 beats/s are heard again. The frequency of B (in Hz) is .......................... 

Answer 1

The frequency of B = ±= 320 4 316 or 324 .

When some wax is added to B its frequency becomes lower and since again beat produced with A is 4 so, frequency of B cannot be 316 and hence, frequency of B (in Hz) is 324 .