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
$x=\frac{n D \lambda}{d}$
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 $\lambda_{\text {blue }}< \lambda_{\text {green }}$
$\therefore x_{\text {blue }} < x_{\text {green }}$