A planar cross section through two spherical waves emanating from the sources S₁ and S₂ in the plane is shown in the figure. The black circles are one and two wavelengths from their respective sources. The lighter circles are one-half and one-and-a-half wavelengths distant from their respective sources. If the phase at S₁ and S₂ is zero at this instant, and the waves shown arriving at P₂ both arrive with amplitude A, the difference in phase angle at point P₂ (in radians) is A)0. B)π/2. C)π. D)3π/2. E)2π.

Question

Quizplus · Accepted Answer

At point P₂, the difference in path length from the two sources is one wavelength. Therefore, the phase difference between the two waves is π radians. Since both waves have the same amplitude and are in phase at their respective sources, the phase angle difference at point P₂ is π radians. Hence, the answer is (C).

A Planar Cross Section Through Two Spherical Waves Emanating from the Sources