The intensity of sound from a point source is `1.0 xx 10^-8 Wm^-2`, at a distance of 5.0 m from the source. What will be the intensity at a distance of 25 m from the source ?

Answer

A, B, D

Explanation

Here `I_1=1.0xx10^-8 w_1/m^2, I_2=?`
`r_1=5.0m, r_2=25m`
We know that
`Iprop(1/r^2)`
`rarr I_1r_1^2=I_2r_2^2`
`rarr I_2=(I_2r_1^2)/(r_2^2)=(1.0xx10^-8xx25)/(625)`
`=4.0xx10^-10W/m^2`