A blue laser beam of wavelength 470nm (in air) is incident on two narrow slits separated by .2mm and produces an interference pattern on a screen located 2m away from the two slits.
Find the angular position (in degrees) of the 1st dark fringe. Can you use the small angle approximation?
The Attempt at a Solution
I've searched all over for a formula to find the dark fringes, but all i can find is one for the light ones. the dsin(theta)=n(lambda) is used for the maxima. what formula do i use for the minima/dark fringes?