Question

A tuning fork produces 4 beats per second with another tuning fork of frequency 256 Hz. The first one is now loaded with a little wax and the beat frequency is found to increase to 6 per second. What was the original frequency of the tuning fork?

Answer 1

A tuning fork produces 4 beats with a known tuning fork whose frequency =256 Hz

So the frequency of unknown tuning fork

=either 256

=4-252 or 256+4

=260 Hz

Now as the first one is loaded its mass/unit length increases. So its frequency decreases.

As it produces 6 beats now original frequency must be 252 Hz.\

260 Hz is not possible as on decreasing the frequency the beats decrease which is not allowed here.