Question

A source emitting light of wavelengths 480 nm and 600 nm is used in. a double slit interference experiment. The separation between the slits is 0.25 mm and the interference is observed on a screen placed at 150 cm from the slits. Find the linear separation between the first maximum (next to the central maximum) corresponding to the two wavelengths.

Answer 1

We know that, the first maximum (next to central maximum) occurs at y =λD/d

Given that, λ₁ = 480 nm, λ₂ = 600 nm, D = 150 cm = 1.5 m and d = 0.25 mm = 0.25x10^–3 m​

So, the separation between these two bright fringes is given by,
separation = y₂ – y₁ = 3.60 – 2.88 = 0.72 mm.