Bit with beats
In a festival a big ground is arranged for several functions at certain moment in the four boxes at 4 corners a shrill sound started due to some technical problems, the 4 boxes had different frequencies as 200,201,204,206 Hz respectively, then calculate the numbers of beats per second as heard by all the irritated audiences.
The answer is 12.
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1 solution
Consider 1 - 1 interference one by one
For the 2 waves interfering find beat frequency , then make a table of time at with beats will be heard(consider an interval of 1 second). Repeat it for all 6 combinations . Then count the distinct beats (max amplitude ) !
That is
For 200 and 201 Hz, the beat frequency is 1 .That implies at t = 1 sec.
For 200 and 204 Hz, the beat frequency is 4. That implies at t = 0.25, 0.50, 0.75, 1.00 second.
Similarly you have to take 6 cases .
But remember at t = 1 sec , all the beats will sound like one . Similarly you will get more such t's.