The noble metal Ag film sample was prepared by the RF (radio frequency) sputtering method. The complex dielectric function and the complex refractive index of the thick Ag film sample were measured by the spectroscopic ellipsometric method in the 1.5 - 4.5 eV photon energy region. The light refractions at the Ag/air interface for a plane film structure were analytically calculated at three different wavelengths. From the calculation, it was found that the refraction angle at the air side is not equal to the initial incidence angle, which is against the experimental observations. The pseudo refractive index and the real refractive angle related to the wavelength, optical constant and incidence angle are always positive in the whole spectrum range. The results given in this work show that more experimental and theoretical studies will be required to understand the properties of light propagation at the metal interface in the future.