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 destructive 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 destructive interference, the two waves must be exactly out of phase, which means that one wave must be shifted by half a wavelength (180 degrees) relative to the other. Therefore, the two beams must travel paths that differ by an odd number of half-wavelengths. Choice B is the only option that satisfies this condition.

Two Beams of Coherent Light Start Out at the Same