Two light sources are said to be coherent if they are
A)of the same frequency.
B)of the same frequency,and maintain a constant phase difference.
C)of the same amplitude,and maintain a constant phase difference.
D)of the same frequency and amplitude.

Question

Quizplus · Accepted Answer

Coherence between two light sources requires that they have the same frequency and maintain a constant phase difference. The amplitude can vary as long as the frequency and phase remain consistent. Choice A is therefore incorrect since frequency alone is not enough to ensure coherence. Choice C is incorrect because amplitude does not have to be the same for coherence. Choice D is also incorrect since amplitude alone is not enough to ensure coherence.

Two Light Sources Are Said to Be Coherent If They