a small stereo amplifier produce a sound of 50 db at a dista

a small stereo amplifier produce a sound of 50 db at a distance of 20 ft from speaker Used formula sound level = 10.log (1.10^12) db If the intensity just found is doubled what happens to the sound level? What must insensitive be to double the sound level to loo db?

Solution

Sound level = 10 log (I *10^(12) = 10 log I + 120

When intensity is doubled

I = 100 db

Then sound level = 10 log(100) +120 = 140 db (ans)

For sound level to be doubled =100 db

10 log I +120 = 100

10 log I = -20

log I = -2

I = 1/100 =0.01 db (ans)