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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 energyflow density averaged ove an oscillation period. |
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Answer» Solution :`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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