Four harmonic waves of equal frequencies and equal intensities I0 have phase angles 0,π3,2π3andπ. When they are superposed, the intensity of the resulting wave is nI0. The value of n is ___
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Solution
Suppose amplitude of individual harmonic wave be A and intensity be l0. When they are super imposed such that first and fourth wave produce destructive interference, while 2nd and 3rd form constructive interference only as shown in phaser method.
So, resultant amplitude, A2r=A2+A2+2.A.A.cos60∘ A2r=3A2 ∴ Intensity of the resulting wave, Ir=3l0 [∴ Intensity of a wave, l=A2]