Question

A string under a tension of `100 N` , emitting its fundamental mode , gives `5 beats//s` with a tuning fork. When the tension is increased to `121 N`, again `5 beats//s` are heard. The frequency of the fork is
A. `105 Hz`
B. `95 Hz`
C. `210 Hz`
D. `190 Hz`

Answer 1

Correct Answer - A
`f prop sqrt(T)`
`(f + 5)/( f - 5) = sqrt((121)/(100))`
`10 f + 50 = 11 f - 55`
`f = 105 Hz`