Assertion:- In standard YDSE set up with visible light, the position on screen where phase difference is zero appears bright.
Reason:- In YDSE set up magnitude of electromagnetic field at central bright frings is not varying with time.

Options

A. If both Assertion `&` Reason are True `&` the Reason is a correct explanation of the Assertion.
B. If both Assertion `&` Reason are True but Reason is not a correct explanation of the Assertion.
C. If Assertion is True but the Reason is False.
D. If both Assertion `&` Reason are False.

Answer

C

Explanation

For zero phase difference, maxima occurs in YDSE and intensity of given light becomes constant which is `(sqrt(I_(1))+sqrt(I_(2))_^(3)`. At this point toal energy also remains constant.
i.e. `((1)/(2)epsilon_(0)E^(2)+(B^(2))/(2mu_(0)))xxVol^(m)`=contant
Hence magnitude of electromagnetic field at central bright remains constant.