Answer:
λ = 3.62 x 10⁻⁷ m = 362 nm
Explanation:
The grating equation gives the relationship between the wavelength, the diffraction line order and the diffraction angle. The grating equation is written as follows:
mλ = d Sinθ
where,
m = order of diffraction = 6
λ = longest wavelength = ?
d = 1/(460 rulings/mm)(1000 mm /1 m) = 2.17 x 10⁻⁶ m/ruling
θ = Diffraction angle = 90° (for longest wavelength)
(6)λ = (2.17 x 10⁻⁶ m/ruling) Sin 90°
λ = (2.17 x 10⁻⁶ m/rulings)/6
λ = 3.62 x 10⁻⁷ m = 362 nm
