Let the intensity of sound hear by observer is I
120=10log1010−12I
12=logI−log1010−12
=logI+12
logI=0⇒I=1m2watt
I=4πr2P
⇒1=4πr22⇒r=2π1=0.4m=40cm
A small speaker delivers 2W of audio output. At what distance from the speaker will one detect 120dB intensity sound? [Given reference intensity of sound as 10−12W/m2 ]
Held on 12 Apr 2019 · Verified 6 Jul 2026.
40cm
20cm
10cm
30cm
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