A tuning fork of frequency 480 Hz produces 10 beats/* when sounded with a vibrating sonometer string. What must have been the frequency of the string if a slight increase in tension produces fewer beats per second than before?
(A) 480 Hz
(B) 490 Hz
(C) 460 Hz
(D) 470 Hz
The correct option (D) 470 Hz
Explanation:
Let n = frequency of sonometer wire.
if n > 480 then n – 480 = 10.
on increasing tension, n increaser. Then according to above relation,
n < 480
∴ 480 – n = 10 or n = 470Hz
