Question

The Young's double slit experiment is performed with blue and green light of wavelengths $4360\mathring{A}$ and $5460\mathring{A}$ respectively. If $x$ is the distance of 4th maxima from the central one, then

• A. $x_{\text{blue }}=x_{\text{green }}$
• B. $x_{\text{blue }}>x_{\text{green }}$
• C. $x_{\text{blue }}<x_{\text{green }}$
• D. $x_{\text{blue }}/x_{\text{green }}$

Answer 1

Answer: (C)

In Young's double slit experiment position of bright fringes on the screen are given by
$x=\frac{nD\lambda }{d}$
Hence, distance of $n$th maxima will be
$x=n\lambda \frac{D}{d}\propto \lambda$
${\lambda }_{\text{blue }}=4360\mathring{A}$
${\lambda }_{\text{green }}=5480\mathring{A}$
$x=$ distance of 4 th maxima from the central are
As ${\lambda }_{\text{blue }}<{\lambda }_{\text{green }}$
$\therefore x_{\text{blue }}<x_{\text{green }}$