Decibel level from source at 1.0 m is 60.0 dB
Find dB level at distance 2.0 m.
dB = 10 log10 (I/I0) <- this one I know but couldn't see an application.
Forgot to add that I0 is equal to 1.0 x 10^-12 W/m^2
dB = dBi - 20 log10 (r2/r1), where r2 is the farther sound source and r1 is the closer one.
The Attempt at a Solution
I arrived at the correct answer of 54.0 dB by using the looked up formula. But I'd rather know how to derive that formula that relates the source distances myself. I tried for a while but am unable to do it. Anyone able to give me some insight on how to arrive at the second formula?