Light passes through a 200 line/mm grating and is observed on a 1.0 m wide screen located 1.0 m behind the grating. Three bright fringes are seen on both sides of the central maximum. What are the minimum and maximum possible values of wavelength?
d= 1mm/200 lines = 5.0e-6 meters
The Attempt at a Solution
I think I got the maximum value:
The maximum value is where the m=3 bright fringe is on the edge of the screen, so the angle is arctan(.5/1) theta= 26.56 degrees. Then dsin(theta)=m*lambda
(5.0e-6)sin(26.56)=3* lambda lambda= 7.45e-7 meters= 745 nm
But for the minimum, I can't figure out what kind of relationship to set up.