This is not a homework problem but a general problem I've been having when studying for physics. What is the formula for "thickness" for thin film interference problems? I read somewhere that there are a variety of equations that can be used--depending on interferences, and etc--however, I just need a solid list of formulas. I've looked through my book and the Internet, and I'm finding a variety of formulas, but none of these sources tell me when to apply each specific thickness formula. Can anyone provide a list of formulas and when to use them? I would greatly appreciate any assistance!