Two beams of coherent light start out at the same point in phase and travel different paths to arrive at point P.If the maximum constructive interference is to occur at point P,the two beams must travel paths that differ by
A)a whole number of wavelengths.
B)an odd number of half-wavelengths.
C)a whole number of half-wavelengths.

Question

Quizplus · Accepted Answer

For maximum constructive interference, the crests of both waves must arrive at point P at the same time. This means that the difference in the distance traveled by the two waves must be an integer multiple of the wavelength. Therefore, the two beams must travel paths that differ by a whole number of wavelengths. Option A is the best choice.

Two Beams of Coherent Light Start Out at the Same