Each of the two strings of length `51.6 cm` and `49.1 cm` are tensioned separately by `20 N` force. Mass per unit length of both the strings is same and equal to `1 g//m`. When both the strings vibrate simultaneously, the number of beats is

Options

A. 3
B. 5
C. 7
D. 8

Answer

C

Explanation

`Deltav=(V)/(2l_(1))-(V)/(2l_(2))=(V)/(2)[(1)/(l_(1))-(1)/(l_(2))]`
`=(1)/(2)sqrt((T)/(mu)){(1)/(l_(1))-(1)/(l_(2))}`