Question

A light with a second-order bright band forms a diffraction angle of 30.0°. The diffraction grating has 250.0 lines per mm. The wavelength of the light is nm.

Answer 1

The wavelength of the light isi 1000Nm

Answer 2

Answer : wavelength, λ = 1000 nm

Explanation :

It is given that,

Diffraction angle, $\theta=30\ ^0$

The diffraction grating has 250 lines per mm\

For bright band the equation of grating is given by :

$dsin\theta=n\lambda$

n = order, here n is 2

Since, d = 1/N

$\lambda=\dfrac{sin\theta}{Nn}$

$\lambda=\dfrac{sin(30)}{250000\ m\times 2}$

λ = 0.000001 m

or

λ = 1000 nm

So, the wavelength of the light is 1000 nm.