Question

The intensity of a sound decreases by a factor of 4. As a result, the sound intensity level decreases by___.
A.4dB
B.6dB
C.8dB
d.16dB

Answer 1

Answer:

 Option B is the correct answer.

Explanation:

 We have expression for sound intensity level,

                  $L=10log_{10}\frac{I}{I_0}$, where I is the intensity.

Here new intensity is given by 4I.

So, increase in  sound intensity level

        $\delta L=10log_{10}\frac{4I}{I_0}-10log_{10}\frac{I}{I_0}=10log_{10}\frac{4I}{I}=6dB$

So, option B is the correct answer.