A tuning fork A, marked 512 Hz, produces 5 beats per second, when sounded with another unmarked tuning fork B. If B is loaded with wax, the number of beats is again 5 per second. What is the frequency of tuning fork B when not loaded?

Explanation

Frequency of tuning fork A = 512 Hz No. of beats per second = 5
`therefore` Frequency of tuning fork `B = 512 +- 5 = 517` Hz or 507 Hz
On loading the tuning fork B with wax, the number of beats remains 5.
Frequency of tuning fork B = 517 Hz
(Because after loading tuning fork B, its frequency decreases from 517 to 512 and number of beats per second remains same.)
Therefore, frequency of B before loading is 517 Hz.