Monochromatic light is incident on a grating that is 75 mm wide and ruled with 50,000 lines. The second-order maximum is seen at 32.5°. What is the wavelength of the incident light? 202 nm 605 nm 806 nm 403 nm 452 nm

= 403 nm

Explanation:

We have the condition for the maximum for a diffraction grating

d sinθ = mλ

Then the grating constant d = w/N

= (75 mm) / (50,000)

= 0.0015 mm

Then wavelength of light is λ = (dsinθ) / m

= (0.0015 mm) (sin 32.5) / 2

=403*10-6 mm

= 403 nm