Question

In Young's double slit experiment, the constant phase difference between two sources is $\frac{\pi }{2}$. The intensity at a point equidistant from the slits in terms of maximum intensity $I_{\circ }$ is :

• A. $I_{\circ }$
• B. $I_{\circ }/2$
• C. $3I_{\circ }/4$
• D. $3I_{\circ }$

Answer 1

The correct option is B $I_{\circ }/2$

If there is no phase difference let
the Intensity equal to maximum Intensity be $I_0$
For a phase difference $\theta$ then
Intensity at a point equidistant from the two
slits is given by
$\frac{I_0}{2}(1+co{s}^2\theta )$
As $\theta =\pi /2$
we get $\frac{I_0}{2}(1+0)=\frac{I_0}{2}$
Thus Intensity $=\frac{I_0}{2}$