A point source emits sound equally in all directions in a non-absorbing medium. Two points P and Q are at distance of 2m and 3m respectively from the source. The ratio of the intensities of the waves at P and Q is :

Question

Dr. Abubacker · Accepted Answer

[Solution from source] A point source spreads energy over a sphere, so I ∝ 1/r². I_P/I_Q = (3/2)² = 9/4, i.e. 9 : 4. Writing 4 : 9 inverts the ratio by taking I ∝ r². Answer (1).

Q. A point source emits sound equally in all directions in a non-absorbing medium. Two points P and Q are at distance of 2m and 3m respectively from the source. The ratio of the intensities of the waves at P and Q is :

Explanation

Reviewed by Dr. Abubacker

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