A tuning fork A produces 4 beats per second with another tuning fork B of frequency 320 Hz. On filing one of the prongs of A, 4 beats per second are again heard when sounded with the same fork B. Then the frequency of the fork A before filing is

Options

A. 328 Hz
B. 316 Hz
C. 324 Hz
D. 320 Hz

Answer

B

Explanation

`n_(A)=n_(B)pm 6=320 pm 4=324` Hz or 316 Hz.
As frequency of A increases on filing therefore the frequency of A before filing is 316 Hz.