Question

2. Light of wavelength 633 nm is incident on a narrow s .diffraction on one side of the central maximum and the first minimum on the other side is lit. The angle between the first 1.20°. What is the width of the slit?

Answer 1

The first diffraction on either side of the central maximum is a minima, Hence here we have to find the width of central maximum, which is given by formula :

ø = 2θ = 2arcsin λ/d

Where, λ = wavelength = 6.33 × 10^-7 m

d = slit width

Given, ø = 1.2°

Putting values,

sin(1.2/2) = 6.33×10^-7 / d

d = 6.33×10^-7 / sin(0.6)

d = 6.02 × 10^-5 m

The slit width is = 6.02×10^-5 m.