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1. The electrical field component of an EM wave is given by E
o
exp[j(kz

ω
t)]. Prove that the
phase velocity is
ω
/k. The phase velocity is the velocity of the wavefront of constant phase, i.e.,
kz
–
ω
t = constant. One way to imagine a wavefront is to look at the waves on the surface of
water and see how the wavefronts (peaks) move or propagate. In doing so, you need to be
aware that the wave on the water surface is a surface acoustic wave; it is not an EM wave.
2. The Poynting vector,
E
x
H,
gives the instantaneous energy flux carried by an EM wave. The
energy flux is energy per cross section area per second. For an EM wave having electrical field
component of
E
= (1, 0, 0) E
o
cos(kz

ω
t), find
H.
Furthermore, derive <
E
x
H>
and express it in
terms of
η
and E
o
only, here
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This note was uploaded on 12/13/2010 for the course ELECTRICAL EECS 145A taught by Professor Chinc.lee during the Fall '10 term at UC Irvine.
 Fall '10
 ChinC.Lee

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