wave_mechanics Beats Question 35

Question: On sounding tuning fork A with another tuning fork B of frequency 384 Hz, 6 beats are produced per second. After loading the prongs of A with some wax and then sounding it again with B, 4 beats are produced per second. What is the frequency of the tuning fork A

[MP PMT 2000]

Options:

A) 388 Hz

B) 380 Hz

C) 378 Hz

D) 390 Hz

Show Answer

Answer:

Correct Answer: D

Solution:

nA = ?, nB = 384 Hz x = 6 bps, which is decreasing (from 6 to 4) i.e.

x¯ Tuning fork A is loaded so nA¯ Hence nA¯ ? nB = x¯ Correct nB ? nA¯ = x¯ Wrong

Therefore nA = nB + x = 384 + 6 = 390 Hz.