(a) The power of sound from the speaker of a radio is 20mW . By training the knob of volume control the power of sound is increased to 400mW . What is the power increase in dB as compared to original power ? (b) How much more intensive is an 80dB sound than a 20dB whisper ?

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Filo · Accepted Answer

a) As intensity is the power per unit area, for a given source PμI. If L1​ and L2​ are the initial and final loudness levels, then we have                             L2​−L1​=10log(I2​/I1​) The increase in loudness level is                                           ΔL=10logP1​P2​​=10log20400​ ⇒            ΔL=10[log20]=13dB (b). Increase in loudness level of sound is                   L2​−L1​=10log(I2​/I1​) ∴            80−20=10log(I2​/I1​) ⇒                     6=log(I2​/I1​) ⇒                     (I1​I2​​)=106

Question Text	(a) The power of sound from the speaker of a radio is $20 mW$ . By training the knob of volume control the power of sound is increased to $400 mW$ . What is the power increase in dB as compared to original power ? (b) How much more intensive is an $80 d B$ sound than a $20 d B$ whisper ?
Answer Type	Text solution:1
Upvotes	150

(a) The power of sound from the speaker of a radio is $20 mW$ . By training the knob of volume control the power of sound is increased to $400 mW$ . What is the power increase in dB as compared to original power ? (b) How much more intensive is an $80 d B$ sound than a $20 d B$ whisper ?

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