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Decaying E-Field

  1. Mar 22, 2006 #1
    We are asked to show that we can have a "spatially uniform E-field" in a conductor according to E=Eo*exp(-t/tau) where tau=ErEo/sigma

    where Er is the relative permittivity and sigma is the conductivity. I know we need to use curl(H) = ErEo*dE/dt + sigma*E
    and for some reason we say that curl H is equal to zero. then we get a simple ODE to solve. I'm having trouble coming up with a geometrical argument for why curl(H) = zero. any hints appreciated.
     
  2. jcsd
  3. Mar 22, 2006 #2

    Physics Monkey

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    If the electric field is spatially uniform, what does the [tex] \nabla \times E = - \frac{\partial B}{\partial t} [/tex] equation imply about [tex] B [/tex] and [tex] H [/tex]?
     
  4. Mar 22, 2006 #3
    I'm not too sure about the meaning of "spatially uniform". If we just assume that E=E(t) and let it be in say the x direction then we can show that curl(E) has no x components, and the rest of the problem works out. But surely a wave has to have some spatial dependence e.g E = E(z,t)?
     
  5. Mar 22, 2006 #4

    Physics Monkey

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    Nope, spatially uniform means independent of position. Indeed, as you show here, spatially uniform solutions do exist though of course they are ultimately unphysical.
     
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