Question

1)The sound level at a distance of 1.82 m from a source is 146 dB. At what distance will the sound level be 50.7 dB? Answer in units of m. 2)At what distance will the sound level be 7.22 dB? Answer in units of m.

Answer 1

power of source

B = 10 log ( I/ 10^-12)

146 = 10og (I/ 10^-12)

I = 398.1 W/m^2

P/ ( 4 pi * 1.82^2) = 398.1

P = 16562.75 W

=====

a) if B = 50.7

50.7 = 10 log (I1/ 10^-12)

I1 = 1.175 * 10^-7

16562.75 / (4pi r^2) = 1.175* 10^-7

r = 1.06* 10^5 m

====

b)

similarly

16562.75 / ( 4 pi r^2) = 10^-12* 10^7.22

r = 1.58* 10^7 m

====

Comment before rate in case any doubt, will reply for sure.. goodluck