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A person speaking normally produces a so...

A person speaking normally produces a sound intensity of 40dB at a distance of 1m. If the threshold intensity for reasonable audibility is 20dB, the maximum distance at which a person can be heard clearly is (2x) meter . Find the value of x.

A

4 m

B

5 m

C

10 m

D

20 m

Text Solution

Verified by Experts

The correct Answer is:
B
`40=10log(10)((I_1)/(I_0))`
`(I_1)/(I_0)=10^4`
Also, `20=10log_(10)((I_2)/(I_0))`
`implies(I_2)/(I_0)=10^2` .(ii)
`(I_2)/(I_1)=10^-2=(r_1^2)/(r_2^2)`
`r_2=100r_1^2impliesr_2=10m`
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