Let 580 nm light be incident normally on a diffraction grating for which d=3.00D=1050nm. a) how many order (principal maxima) are present ? b) if the grating is 1.80 cm wide, what is the full angular width of each principal maximum?
I got the first part I just plugged into dsin(θ)=mλ which is 1050sin(90)=m*580 but i really don't know what to do on the second part. I tried the equation Δθ=λ/Ndcosθ