A grating is made of five similar, uniformly spaced, narrow slits. For light of wavelength ? = 675 nm perpendicularly incident on the slits, the angular position of the first principal order is 21° to the normal. What is the slit separation?
What is the angular position of the first principal order when the first and fifth slits are covered?
What is the angular position of the first principal order when the second and fourth slits are covered?