Question

In the figure shown is a parallel beam of white light incident on the plane of the slits. The distance of the nearest white spot on the screen from $O$ is : [ assume $d<<D,\lambda <<d$]

• A. $0$
• B. $\frac{d}{2}$
• C. $\frac{d}{3}$
• D. $\frac{d}{6}$

Answer 1

The correct option is D $\frac{d}{6}$


We know that $P$ will be the central maxima, where path difference is zero.

Now, by the geometry of the figure,

$OP=\frac{2d}{3}-\frac{d}{2}=\frac{d}{6}$

Hence, $\left(D\right)$ is the correct answer.