GREPhysics.NET: GR9277 #34

GR9277 #34

Problem

GREPhysics.NET Official Solution

\prob{34}
A conudcting cavity is driven as an electromagnetic resonator. If perfect conductivity is assumed, the transverse and normal field components must obey which of the following conditions at the inner cavity walls?

$E_n=0$ , $B_n=0$
$E_n=0$ , $B_t=0$
$E_t=0$ , $B_t=0$
$E_t=0$ , $B_n=0$
None of the above

Electromagnetism $\Rightarrow$ }TEM Waves

The full formalism of a conducting cavity can be solved via TEM (transverse electromagnetic) wave guides. However, to solve this problem, one needs only the two boundary conditions from the reflection at a conducting surface, $\Delta E_{\parallel} = 0$ and $\Delta B_{\perp}=0$ .

The electric field parallel to the cavity is the transverse field, and thus one has choice (D), exactly the conditions above.

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Comments

chrisfizzix
2008-10-06 12:16:10

Conducting cavity = waveguide. You can find the first condition $E_t = 0$ without knowing anything about waveguides by remembering that in a perfect conductor there can't be an electric field parallel to the surface.

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sirius
2008-06-24 14:27:26

i have never heard of conducting cavities, what topic is this from? is there a text i should look at for this?

Poop Loops
2008-10-05 15:22:16

Griffiths E&M covers it.

GREmania
2008-10-12 07:30:31

Looks like most of the problems are related to Griffiths Stuff.

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kevglynn
2006-09-25 12:28:15

Could someone explain what a conducting cavity is (in general terms, an example of one, etc.)? Also, when it comes to the boundary conditions, what are the others?

Thanks

kevglynn
2006-10-15 19:16:01

nevermind, must have been groggy that morning. feel free to edit this out ;-)

p.s. Yosun is the man

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