Question

Two pieces of window glass are separated by a distance, d. If a beam of light of wavelength l=469 nm passes through the first piece of glass. What is the minimum distance, in nm, such that the light intensity transmitted through the right is a maximum?

Answer 1

The distance needs to be optimized to cause constructive interference, which can be seen on the following drawing:

So the distance needs to be exactly of a single wavelength.

Then, our final answer is d=469nm