The penetration depth or skin depth of a medium is the distance at which the amplitude of the electromagnetic wave will decay by a factor of e^?1.
a. Show that the penetration depth is ? = 1/kI , where kI is the imaginary part of the wavenum-ber k.
b. An electromagnetic wave has an average power density of 1 W/m^2 just inside the surface of a lossy medium. What is the power density 1/2Re{¯E × ¯H } at one skin depth ?
c. How much power 1/2Re{ ¯ E · ¯ J} is absorbed by the medium in one skin depth ??
d. Is energy conserved?