Physics · Wave motion, longitudinal and transverse waves, speed of the travelling wave, displacement relation for a progressive wave
A point source emits sound equally in all directions in a non-absorbing medium.
A point source emits sound equally in all directions in a non-absorbing medium. Two points \( P \) and \( Q \) are at distance of \( 2 m \) and \( 3 m \) respectively from the source. The ratio of the intensities of the wave at \( P \) and \( Q \) is:
- A. 9: 4
- B. 2: 3
- C. 3: 2 \)
- D. 4: 9
Step-by-step solution
For a point source in a non-absorbing medium, intensity is inversely proportional to the square of the distance. Thus, I ∝ 1/r². Given r_P = 2 m and r_Q = 3 m, the ratio I_P : I_Q = (1/2²) : (1/3²) = (1/4) : (1/9) = 9 : 4.
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