In electromagnetic waves, the skin depth is the depth at which the amplitude of the electric and magnetic fields have reduced by 1 e . The intensity of the wave is proportional to the square of the amplitude, and thus the depth at which the intensity has diminished by 1 e is δ δ 2 . In waveguides, losses due to induced currents occur mostly within one skin depth of the surface. Thus, plating the surface of a waveguide with a material which has a low skin depth reduces losses.