Two-Slit Interference: Find Slit Separation

[rpedroza]

Homework Statement

Using a conventional two-slit apparatus with light of wavelength 540 nm, 33 bright fringes per centimeter are observed on a screen 3.8 m away. What is the slit separation?

Homework Equations

m/x = (2*theta)/wavelength = number of fringes per meter
interence maxima
dsin(theta) =m*(wavelength)

The Attempt at a Solution

i tried solving for theta then using that value to find slit separation d but i am totally confused.

 

[rpedroza]

i got the answer.
fringe spacing = ((wavelength)*L)/d
L = distance to screen
d = slit separation

the fringe spacing would be the inverse of 33fringes per cm or ((3300)/m)^-1 then just solve for d