Length of a sonometer wire is either 95 cm or 100 cm. In both the cases a tuning fork produces 4 beats then the frequency of tuning fork is :-

Options

A. 156Hz
B. 148Hz
C. 152Hz
D. 160Hz

Answer

A

Explanation

`n_1 gt n gt n_2 therefore n_1-n=4 " and " n- n_2 =4`
`therefore n_1-n_2 = 8 " " n_1l_1=n_2l_2`
`therefore n_1=(n_2l_2)/(l_1)`
`(n_2l_2)/(l_1)-n_2=8 therefore (n_2(l_2-l_1))/(l_1) = 8`
`therefore 5n_2 = 8xx19 = 152`
hence , `n=n_2 +4 = 152 +4 =156Hz`