Question

A sound wave radiates from a source in all directions. If thepower of the sound source is 200 watts, then the intensity level ofthe sound wave 100m from the source is, in dB

Answer 1

We power   P = Intensity *Area

Area =4πR²

R= 100 m

P = 200W

Then Intensity I= P/Area

I = 200W/4π(100m)² = 1.592*10^-3W/m²

We knowthat intensity level β = (10dB) log(I/Io)

Here Io= 10^-12W/m²

Then   β =  (10dB) log(I/Io)

β= (10dB)log( 1.592*10^-3W/m²/10^-12W/m²) =92dB