Question

A beam of light of wavelength 600 nm from a distant source falls on a single slit 1 mm wide and the resulting diffraction pattern is observed on a screen 2 m away. What is the distance between the first dark fringe on either side of the central bright fringe?

Answer 1

${\displaystyle \beta =\frac{\lambda \text{D}}{\text{d}}}$

d = 1 mm

λ = 600 × 10^-9 m

D = 2m

${\displaystyle =\frac{6\times {10}^2\times 10-9\times 2}{1\times {10}^{-3}}}$

= 1.2 mm

Distance between two dark fringes which are on either side of the central bright fringe = 2 × 1.2 mm = 2.4 mm