Diffraction grating – problems and solutions

1. A grating containing 4000 slits per centimeter is illuminated with a monochromatic light and produces the second-order bright line at a 30° angle. What is the wavelength of the light used? (1 Å = 10^{-10} m)

__Known :__

The distance between slits (d) = 1 / (4000 slits / cm) = 0.00025 cm = 2.5 x 10^{-4} cm = 2.5 x 10^{-6} meters

Order (n) = 2

Sin 30^{o} = 0.5

1 Å = 10^{-10} m