Variations in Interference Colours on Copper and Steel

Abstract

THE high values of the refractive index of copper and iron make it probable that only slight changes of colour would be observed on varying the angle of incidence of the light. With burnished metal surfaces, changes of larger magnitude than expected (giving = 2·4 for copper oxide and = 1·8 for iron oxide) were observed with angles of incidence up to 78°, together with strong scattering of the complimentary colours. At larger angles of incidence general reflection predominated, and all colour vanished except a slight effect due apparently to the metal itself.