Question

A sound absorber decreases a sound's loudness from 60 dB to 20 dB. Intensity of sound decreases by a factor of

• A. 100
• B. 10000
• C. 10
• D. 1000

Answer 1

The correct option is B 10000

${\beta }_2-{\beta }_1=10{\text{log}}_{10}\frac{I_2}{I_1}$
$\text{/}20-\text{/}60=\text{/}10{\text{log}}_{10}\frac{I_2}{I_1}$
$-4={\text{log}}_{10}\frac{I_2}{I_1}$
$I_2={10}^{-4}{I}_1$
$\frac{I_2}{I_1}={10}^{-4}$