A stretched sonometer wire is in unison with a uning fork. When the length is increased by 2% the number of beats per second is 5. Find the frequency of the forks.

Explanation

`f prop (1)/(l) , :. (Deltaf)/(f)=-(Deltal)/(l)`
Let f be the frequency of fork
Hence `(5)/(f)xx100=-((Deltal)/(l)xx100)`
`(5)/(f)xx100=2 " " :.f-250Hz`