Thin Films again - Help?

rachiebaby17

1. The problem statement, all variables and given/known data

A camera lens (n = 1.90) is coated with a thin film of magnesium fluoride (n = 1.40) of thickness 90.0 nm. What wavelength in the visible spectrum is most strongly transmitted through the film?


2. Relevant equations

?

3. The attempt at a solution

I have no idea where to start, is there an equation that will use both n's at once?

rl.bhat

Search in Google for thin film interference.