Question

A point source of sound is vibrating with a frequency of 256 vibrations per second in air and propagating energy uniformly in all directions at the rate of 5 joules per second. Calculate the amplitude of the wave at a distance of 25 m from the source. Assume non-dissipative medium `[c=330m//s` & density of air `=1.29kg//m^(3)]`
A. `0.8xx10^(-2)m`
B. `0.8xx10^(-8)m`
C. `10^(-6)m`
D. `10^(-4)m`

Answer 1

Correct Answer - C
`l=2pi^(2)rhovA^(2)upsilon^(2)=(w)/(4pir^(2))`
`thereforeA=[(W)/(8pi^(3)rhovupsilon^(2))]^(1//2).(1)/(r)cong10^(-6)m`