Question

In a Fraunhofer diffraction experiment, a single slit of width $0.5mm$ is illuminated by a monochromatic light of wavelength $600nm$. The diffraction pattern is observed on a screen at a distance of $50cm$ from the slit. What will be the linear separation of the first order minima?

• A. $1.0mm$
• B. $1.1mm$
• C. $0.6mm$
• D. $1.2mm$

Answer 1

The correct option is D $1.2mm$

Let $x$ be the distance between the first order minima's.

$dsin\theta =2\times \lambda /2$

$d\frac{x}{2D}=\lambda \frac{0.5\times x\times {10}^{-3}}{2\times 50\times {10}^{-2}}=1\times 600\times {10}^{-9}$
$\Rightarrow x=1.2mm$