If the amplitude of sound is doubled and the frequency reduced to one-fourth, the intensity of sound at the same point will be :

Options

A. increasing by a factor of 2
B. decreasing by a factor of 2
C. decreasing by a factor 4
D. unchanged .

Answer

C

Explanation

Intensity of wave I = `2pi^(2) rho v^(2) r^(2) v`.
`rArr = I alpha v^(2) r^(2)`.
As amplitude r is doubled and frequency is reduced to one-fourth
`therefore` Intensity of wave becomes `(1)/(4)` th
Hence correct choice is (c).