The power of sound from the speaker of a radio is 20 milli watt b… - Vidyadip

MCQ

The power of sound from the speaker of a radio is $20$ milli watt by turning the knob of the volume control the power of the sound is increased to $400$ milli watt. The power increase in decibles as compared to the original power is ..... $dB$

✓
$13$
B
$10$
C
$20$
D
$800$

✓

Answer

Correct option: A.

$13$

a
$\mathrm{SL}_{2}-\mathrm{SL}_{1}=10 \log \frac{\mathrm{I}_{2}}{\mathrm{I}_{1}}=10 \log \frac{\mathrm{P}_{2}}{\mathrm{P}_{1}}=10 \log \frac{400}{20}$

$=13 \mathrm{\,dB}$

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