Question

Blue light, which has a wavelength of about 475 nm, is made to pass through a slit of a diffraction grating that has 425 lines per mm and forms a first-order bright band. What is the angle of diffraction? Round answer to the nearest whole number.

Answer 1

The formula relating the variables involved is:

distance between lines * sin(angle of diffraction) = order of band * wavelength

dsin(∅) = nλ

The line spacing may be calculated using the fact that there are 425 lines per mm and 1 mm contains 0.001 m

d = 0.001 / 425 = 2.35 x 10⁻⁶ m
λ = 475 x 10⁻⁹ m

Substituting the values,

2.35 x 10⁻⁶ * sin(∅) = 1 * 475 x 10⁻⁹ 
∅ = 11.7°


The angle of the first order bright band, or maxima, is 11.7°

Answer 2

round your answer to 12