A wire of diameter `0.04 cm` and made of steel of density `8000 kg//m^(3)` is under a tension of `80 N`. A fixed length of `50 cm` is set into transverse vibrations . How would you cause vibrations of frequency `840 Hz` to predominate in intensity ?

Answer

`[(1)/(6) point is to be plucked ]`

Explanation

Fundametal frequency of wire is
`h_(0) = (1)/(2l)sqrt((T)/(rhoS))`
= `(1)/(2 xx 0.5) xx sqrt((79xx4)/(8000 xx3.14 xx(0.04 xx10^(-2))^(2)))`
= 280 Hz.
Thus to setup 840Hz, wire should setup in third harmonic for which wire must be supported at `l//3` point from one end and plucked at `l//6` point to setup oscillations.