question_answer

In the adjacent diagram, CP represents a wave front and AO & BP, the corresponding two rays. Find the condition on 0 tor constructive interference at P between the ray BP and reflected ray OP.

A) \[\cos \theta =3\lambda /2d\]     

B) \[\cos \theta =\lambda /4d\]

C) \[\sec \theta -\cos \theta =\lambda /d\]     

D) \[\sec \theta -\cos \theta =4\lambda /d\]