Two waves,one with amplitude A and the second with amplitude 2A,are in phase.The resultant intensity is A)zero B)A C)3A D)3A² E)(3A)²

Question

Quizplus · Accepted Answer

The intensity of a wave is proportional to the square of its amplitude. When two waves are in phase, their amplitudes add before squaring. Thus, the resultant amplitude is $A + 2A = 3A$, and the intensity, being proportional to the square of the amplitude, is $(3A)^2$.

Two Waves,one with Amplitude a and the Second with Amplitude