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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. |
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Answer» `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)` |
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