An electromagnetic wave propagating in seawater has an electric field whose time variation is given by E = z . 1 0 . coswt . If the electrical permittivity of water is 4 0 ɛ 0 and its conductivity is 6 ( S m ) , find the ratio of the conductivity current density to the displacement current density for each of the following frequencies.
( a ) 1 0 kHz
( b ) 1 MHz
( c ) 1 GHz
( d ) 1 0 0 GHz