A hollow metallic tube of length L and closed at one end produce resonance with a tuning fork of frequency n. The entire tube is then heated carefully so that at equilibrium temperature its length changes by `l`. If the change in velocity V of sound is v, the resonance will now produced by tuning fork of frequency :-

Options

A. `(V + v)//(4(L +l))`
B. `(V+v)//(4(L-l))`
C. `(V-v)//(4(L+l))`
D. `(V-v)//(4(L-l))`

Answer

A

Explanation

For closed tube
`(lamda)/(4)=(V)/(4f)=L and (lamda')/(4)=(V+v)/(4f')=L+lrArrf'=(V+v)/(4(L+l))`