Question

A fork A has frequency `2%` more than the standard fork and B has a frequency `3%` less than the frequency of same standard frok. The forks A and B when sounded together produced 6 beats/s. The frequency of fork A is
A. `116.4 Hz`
B. `120 Hz`
C. `122.4 Hz`
D. `238.8 Hz`

Answer 1

Correct Answer - C
The frequency of `A,n_A=n+(2)/(100)n`
And the frequency of `B,n_B=n-(3)/(100)n`
According to question `n_A-n_B=6`
`:. (n+(2)/(100)n)-(n-(3)/(100)n)=6`
or `(5)/(100)n=6impliesn=(600)/(5)=120Hz`
The frequency of A
`n_A=(n+(2)/(100)n)=120+(2)/(100)xx120=122.4Hz`