A sound absorber attenuates the sound level by `20 dB`. The intensity decreases by a factor of

Options

A. (a) `100`
B. (b) `1000`
C. (c ) `10000`
D. (d) `10`

Answer

A

Explanation

(a) We have, `L_(1) = 10 log((I_(1))/(I_(0)))`, `L_(2) =10 log((I_(2))/(I_(0)))`
:. `L_(1) - L_(2) = 10 log((I_(1))/(I_(0))) - 10log((I_(2))/(I_(0)))`
or, `DeltaL = 10 `((I_(1))/(I_(0)) xx( I_(0))/(I_(2)))` or, `DeltaL = 10 log (I_(1)/(I_(2)))`
or, `20 = 10 log((I_(1))/(I_(2))` or, `2 = log((I_(1))/(I_(2))`
or, `(I_(1))/(I_(2)) = 10^(2)` or, `I_(2) = (I_(1))/(100)`.
rArr Intensity decreases by a factor `100`.