I believe that there are two potential equations that could help you. I am by no means great at this (since we also are going over it, and i have a test tomorrow) but i think the equations given to me may help.
{ } + (2dn2)/λ = m this is for constructive
{ } + (2dn2)/λ = m + 0.5...
Homework Statement
Light from a He-Ne laser (\lambda = 632.8nm) strikes a pair of slits at normal incidence, forming a double-slit interference pattern on a screen located 1.50 from the slits. The figure shows the interference pattern observed on the screen
What is the slit separation...