Optics Question 137
Question: In the adjacent diagram, CP represents a wavefront and AO & BP, the corresponding two rays. Find the condition on q for constructive interference at P between the ray BP and reflected ray OP
[IIT-JEE (Screening) 2003]
Options:
A) cosq = 3l/2d
B) cosq = l/4d
C) secq ? cosq = l/d
D) secq ? cosq = 4l/d
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Answer:
Correct Answer: B
Solution:
Therefore PO = d secq and CO = PO cos 2q
Phase difference between the two rays is f = p (One is reflected, while another is direct)
Therefore condition for constructive interference should be
Therefore
