1. The problem statement, all variables and given/known data Light of wavelength 470 nm passes through a block of material with a refractive index n = 1.30, some of it is reflected off the air-block boundary and some of it is transmitted through air (n=1.00) with thickness t, and is then reflected off another block also with n = 1.30. What is the minimum thickness, t, for which you will observe: Constructive interference Destructive intereference 2. Relevant equations t = (m+1/2)*lamda / 2n t = m*lamda / 2n 3. The attempt at a solution m would be 0 since it's asking for minimum thickness, therefore destructive interference would always be zero wouldn't it? I'm a bit confused because another book has the equation: t = (m + 1/2)*lamda / 2 <- what happened to the refraction index?