Problem: A jewelry designer is trying something different: he wants to coat a diamond (n = 2.418) with a thin plastic (n = 1.50) film to cause the diamond to look colored when white light is shone on it.
Part I: Setting lambda = 550 nm as the middle of the visible spectrum, what is the thinnest film thickness that will give enhanced reflection at this wavelength?
Part II: For this thickness, what is the nearest wavelength that will destructively interfere on reflection from the coating?
Rework your solution from the beginning and check each step carefully.