The depth of penetration of electromagnetic wave in a medium having conductivity $$\sigma $$ at a frequency of 1 KHz is 25 cm. The depth of penetration at a frequency of 4 KHz will be

If a plane electromagnetic wave satisfies the equation $${{{\partial ^2}\,{E_x}} \over {\partial \,{z^2}}} = \,{c^2}{{{\partial ^2}\,{E_x}} \over {\partial \,{t^2}}},$$ the wave propagates in the

A TEM wave is incident normally upon a perfect conductor. The E and H fields at the boundary will be respectively

The intrinsic impedance of copper at high frequencies is