Assertion: Two identical waves due to two coherent sources interfere at a point with a phase difference of `(2pi)/3`, then the resultant intensity at this point is equal to the individual intensity of the sources.
Reason: A phase difference of `(2pi)/3` is equivalent to a path difference of `lambda/3`.

Options

A. (a)If both Assertion and Reason are true and the Reason is correct explanation of the Assertion.
B. (b)If both Assertion and Reason are true and the Reason is not the correct explanation of the Assertion.
C. (c) If Assertion is true, but the Reason is false.
D. (d) If Assertion is false, but the Reason is true.

Answer

B

Explanation

`I=4I_0 "cos"^2(phi/2)` ………..(i)
`phi = (2pi)/3 or 120^@ rArr phi/2 = 60^@`
Substituting in Eq. (i), we get
`I=I_0 rArr Deltax = (lambda/(2pi)) phi ` .