A small speaker delivers 2 W of audio output. At what distance from the speaker will one detect 120 dB intensity sound? (Given reference intensity of sound as 10–12 W/m2)
a)
30 cm
b)
40 cm
c)
10 cm
d)
20 cm
a)
30 cm
b)
40 cm
c)
10 cm
d)
20 cm
Question ID - 51565 | SaraNextGen Top Answer A small speaker delivers 2 W of audio output. At what distance from the speaker will one detect 120 dB intensity sound? (Given reference intensity of sound as 10–12 W/m2)
a)
30 cm
b)
40 cm
c)
10 cm
d)
20 cm
A small speaker delivers 2 W of audio output. At what distance from the speaker will one detect 120 dB intensity sound? (Given reference intensity of sound as 10–12 W/m2)
|
a) |
30 cm |
b) |
40 cm |
|
c) |
10 cm |
d) |
20 cm |
1 Answer
127 votes
Answer Key / Explanation : (b) -
120 = 10log10 
⇒ 
⇒ l= 1 W/m2
⇒ r = 
m = 0.399 m
= 40 cm
127 votes
Answer Link
127