What is the wavelength of light falling on double slits separated by 2.00 μm if the third-order maximum is at an angle of 60.0∘?

λ = 5.773 x 10⁻⁷ m = 577.3 nm

Explanation:

In order to solve this problem we will use the grating equation:

mλ = d Sin θ

where,

m = order = 3

λ = wavelength of light = ?

d = slit separation = 2 μm = 2 x 10⁻⁶ m

θ = angle = 60°

Therefore,

(3)λ = (2 x 10⁻⁶ m)Sin 60°

λ = 1.732 x 10⁻⁶ m/3

λ = 5.773 x 10⁻⁷ m = 577.3 nm

b) phosphorus pentoxide