Two coherent sound waves of intensities 9 W/m² and 4 W/m² arrive at the same point with phase difference π. If the resultant intensity is N W/m², find N.
Physics · Wave Motion · sound wave
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Question

Two coherent sound waves of intensities 9 W/m² and 4 W/m² arrive at the same point with phase difference π. If the resultant intensity is N W/m², find N.

G1 Physics · Accepted Answer

For phase difference π, I = I₁+I₂−2√(I₁I₂). Equivalently, I = (√I₁−√I₂)². Thus, I = (3−2)² = 1 W/m². Hence, N = 1.