Sound WavesHardBloom L3
Question
A person hears a single-frequency sound from a speaker that emits sound uniformly in all directions. The person records the decibel level reading. Which of the following processes would increase the decibel reading the most?
Options
A.The power output of the speaker is doubled.
B.The frequency of the sound is doubled keeping amplitude constant.
C.The temperature of the air is doubled on the Kelvin scale.
D.The area over which the sound is transmitted is halved.
Solution
Sol. (A) I = $\frac{P_{0}}{4\pi r^{2}}$
P0 → 2P0 ⇒ I → 2I
(B) I = $\frac{1}{2}$ρA24πf2v
f → 2f ⇒ I → 4I
(C) v = $\sqrt{\frac{\gamma RT}{M}}$
T → 2Τ ⇒ v → $\sqrt{2}$v
⇒ I → $\sqrt{2}$I
(D) I = $\frac{P_{0}}{Area}$
A → $\frac{A}{2}$ ⇒ I → 2Ι
Hence Ans. (B)
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