question_answer

Two tuning forks, 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 [MP PMT 1997]

A)            312 Hz                                     

B)            316 Hz

C)            324 Hz                                     

D)            328 Hz

Correct Answer: C

Solution :

                   nA ? nB¯ = x (same)          ... (i)                Wrong                    nB¯  ? nA = x (same)         ... (ii)               Correct Þ nB = nA + x = 320 + 4 = 324 Hz.