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A person speaking normally produces a sound intensity of `40 dB` at a distance of `1 m`. If the threshold intensity for reasonable audibility is `20 dB`, the maximum distance at which he can be heard cleary is.A. 4 mB. 5 mC. 10 mD. 20 m |
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Answer» Correct Answer - 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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