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knowlewj01
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Homework Statement
A wave is driven at z=0 with constant real frequency ωr propagates in the z direction, for z>0 the amplitude varies as:
[itex]A = A_0 e^{i\omega_r - ikz}[/itex]
where k is complex
[itex]k=k_r - i k_i[/itex]
if a wave with spatially constant amplitude and purely real wavenumber kr were excited in the same medium, how long would pass before the wave's amplitude decreased by a factor of e?
Homework Equations
The Attempt at a Solution
(I'm not too sure what is meant by 'spatially constant')
does anyone know where to start on this one? I've tried a few things like removing the i from ikz, removing the z dependence altogether, I'm having trouble picturing what's going on.