Question

In young’s double slit experiment the two slits are 0.6 mm distance apart. Interference pattern is observed on a screen at a distance 80 cm from the slits. The first dark fringe is observed on the screen directly opposite to one of the slits. The wavelength of light will be _____ nm.

Answer 1

Correct Answer: 450

\(y = \frac d2\)

\(∴ Δ x = y \frac dD\)

\(⇒ \frac {d^2}{2D} =\frac λ2\)

\(⇒ λ = \frac {(0.6 \times 10-3)^2}{0.8}\)

\(⇒ λ = 450\ \text{nm}\)

So, the answer is \(450\ \text{nm}\).