In a single slit diffraction experiment, light of wavelength 600 nm is used and the first minimum is observed at an angle of 30°. The width of the slit is:

Question

Question

This question was previously asked in

AAI ATC Junior Executive 27 July 2022 Shift 2 Official Paper

Answer 1

Concept:

Young’s Single Slit Experiment

In the single-slit experiment, we use a long slit as the source of light in place of pin holes.
The light coming out of the slit is intercepted on a screen placed parallel to the plane of the slits.
The slit is illuminated by a parallel beam of monochromatic light.
A series of dark and bright strips, called fringes, is observed on the screen.
The nth-order minima are given by,
- d sinθ = nλ
Where, d = width of the slit, λ = wavelength, θ = angle, n = nth fringe

Calculation:

Given, wavelength λ = 600 nm, for first minimum angle θ = 30°, n = 1

Then width of the slit, d sinθ = nλ

⇒ d × sin30° = 1 × 600

⇒ d = 600 × 2 = 1200 nm = 1.2 μm