Question

Two tuning fork when sounded together, produce 3 `beats//s`. One of the fork is in unison with `27 cm` length of sonometer wire and other with `28 cm` length of the same wire. The frequencies of the two tuning forks are
A. `87 , 84 Hz`
B. `49, 39 Hz`
C. `81, 78 Hz`
D. `84, 81 Hz`

Answer 1

Correct Answer - D
`n_(1) - n_(2) = 3 "……."(i)`
`n prop (1)/(l)`
`n_(1)l_(1) = n_(2)l_(2)`
`(n_(1))/(n_(2)) = (28)/(27)"…."(2)`
Solving these two equation
`n_(1) = 84 , n_(2) = 81`