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-2013]
(1) 246 Hz
(2) 240 Hz
(3) 260 Hz
(4) 254 Hz​

Answer 1

Answer:

Explanation:

As we know, beats frequency= v1-v2.

Now,here in first case we have unknown frequency as 250+4 or 250-4, depending upon waxing or filing.

Now in second case we have second harmonics. So here unknown frequency is 513-5 =508 or 513+5=518. Now converting frequency of second harmonics,we have 508/4=254.

Hence option 4 is correct.

Regards.