Components of E for a waveguide problem.

atomicpedals
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Homework Statement



For a rectangular wave guide the components of E were found to be

Ex = A1 cos( k1 x) sin(k2 y) e-i (\omegat-\gammaz)

Ey = A2 cos( k1 x) sin(k2 y) e-i (\omegat-\gammaz)

Ez = 0

Show that in these equations A1 = -A2 k2 / k1

Homework Equations



See part (a)

The Attempt at a Solution



My first instinct is simply substitute this given A1 into the x equation and show its equivalence to the second. But I'm not so sure that's the best way to go about it (or even the correct way to go about it). It would be tempting to solve this using matrices but that doesn't seem appropriate.

So, any suggestions as to if I'm on the right track or way off base are much appreciated!
 
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hi atomicpedals! :smile:
atomicpedals said:
Show that in these equations A1 = -A2 k2 / k1

hmm :rolleyes: … that's the same as k1A1 + k2A2 = 0 …

how could you manipulate the original equations to get that? :wink:
 
Aww fer crying out loud, they're vector components (facepalm)... yeah, leave it to me to miss the bleedin' obvious!

Thanks!
 
tiny-tim said:
hi atomicpedals! :smile:


hmm :rolleyes: … that's the same as k1A1 + k2A2 = 0 …

how could you manipulate the original equations to get that? :wink:

I don't get it.
 
The fist thing I failed to see right off the bat was that each equation was a vector component. That is E = ( Ex , Ey , Ez )

So looking at it like that there are a number of ways to get it down to the simple algebraic form (divergence or laplacian ...I'll need to crunch the numbers).
 
Ignoring Ez, in your problem statement you have two equations whos amplitudes are independent. There's a missing constraint.
 
To solve this, I first used the units to work out that a= m* a/m, i.e. t=z/λ. This would allow you to determine the time duration within an interval section by section and then add this to the previous ones to obtain the age of the respective layer. However, this would require a constant thickness per year for each interval. However, since this is most likely not the case, my next consideration was that the age must be the integral of a 1/λ(z) function, which I cannot model.
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