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

Question

A tuning fork A produces 4 beats/s with another tuning fork B of frequency 320 Hz. On filing one of the prongs of A, 4 beats/s are again heard when sounded with the same fork B. Then, the frequency of the fork A before filing is (A) 328 Hz (B) 316 Hz (C) 324 Hz (D) 320 Hz

Tardigrade Admin · Accepted Answer

To have 4 beats per second, f A can be either 316 Hz or 324 Hz. Since filing increases the frequency, beat frequency, f=fB-fA=4 beats per second f A = frequency of fork A before filing f A =320-4=316 Hz

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

328 Hz

316 Hz

324 Hz

320 Hz

To have 4 beats per second, $f_{A}$ can be either $316 Hz$ or $324 Hz$ .
Since filing increases the frequency, beat frequency, $f = f_{B} - f_{A} = 4$ beats per second
$f_{A} =$ frequency of fork $A$ before filing
$f_{A} = 320 - 4 = 316 Hz$

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