Dear All, I have a question about the optical properties of light in a metal. I need to solve a problem. 1. The problem statement, all variables and given/known data a] Why is the phase shift in a metal neither 0 or pi? b] And calculate the phase shift of gold with a wavelength of 514 nm? n_real=0,5 and n_imaginary=1,85, R=0,647 For problem b I can't find the proper equation to calculate the phase shift. I already read Optics of Hecht, but I can't find it in Hecht. They mention it on page 131 but they do not explain it. Thanks in advance!