Question

A plane harmonic electromagnetic wave with plane polarization propagates in vacuum. The elctric component of the wave has a strength amplitude `E_(m)= 50 m V//m`, the frequency is `v=100MHz`. Find `:`
`(a)` the efficient value of the displacement current density ,
`(b)` the mean energy flow density averaged ove an oscillation period.

Answer 1

`E = E_(m)cos (2pi vt - kx)`
(a) `j_(dis) = (delD)/(delt) = - 2pi epsilon_(0)vE_(m)sin (omegat - kx)`
Thus `(j_(dis))_(rms) = lt j_(dis)^(2)gt^(1//2)`
`= sqrt(2) pi epsilon_(0)vE_(m) = 0.20 mA//m^(2)`.
(b) `lt S_(x) gt = (1)/(2) sqrt((epsilon_(0))/(mu_(0))) E_(m)^(2)` as in. Thus `lt S_(x) gt = 3.3 muW//m^(2)`