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Question: Answered & Verified by Expert
A sound absorber attenuates the sound level by $20 \mathrm{~dB}$. The intensity decreases by a factor of
PhysicsWaves and SoundJEE MainJEE Main 2007
Options:
  • A
    $1000$
  • B
    $10000$
  • C
    $10$
  • D
    $100$
Solution:
2130 Upvotes Verified Answer
The correct answer is:
$100$
$\begin{aligned}
& \mathrm{B}_1=10 \log \left(\frac{\mathrm{I}}{\mathrm{I}_0}\right) \\
& \mathrm{B}_2=\log \left(\frac{\mathrm{I}^{\prime}}{\mathrm{I}_0}\right)
\end{aligned}$
given $B_2-B_1=20$
$\begin{aligned}
& 20=10 \log \left(\frac{\mathrm{I^{\prime}}}{\mathrm{I}}\right) \\
& \mathrm{I}^{\prime}=100 \mathrm{I}
\end{aligned}$

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