A tuning fork vibrating with a sonometer having 20 cm wire produces 5 beats per second. The beat frequency does not change if the length of the wire is changed to 21 cm. The frequency of the tuning fork (in Hertz) must be

Options

A. 200
B. 210
C. 205
D. 215

Answer

C

Explanation

`fprop(1)/(l)`
`f_(1)l_(1)=f_(2)l_(2)`
`implies (N+5)xx20=(N-5)xx21`
N `rarr` frequency of tunning fork be N
implies N = 205 Hz.