Question

A source of unknown frequency gives 4 beats/s,
when sounded with a source of known frequency
250 Hz. The second harmonic of the source of
unknown frequency gives five beats per second,
when sounded with a source of frequency 513 Hz.
The unknown frequency is
[NEET-20131
1)​

Answer 1

source of frequency 250 Hz, Second harmonic of this unknown source = 492 Hz or 508 Hz which gives 5 beats per second.