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Displacement current density... watch

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    Hi, just to check which equation for Jd (the displacement current density) is correct:

    1) Jd = ε0εr(dE/dt), or
    2) Jd = ε0(εr-1)(dE/dt)

    1) came from the fact that Jd = ε(dE/dt) and ε=ε0εr
    2) came from differentiating P = ε0(εr-1)E (since Jd=dP/dt).

    It's only a minor thing but in a question I'm doing, it gives a different answer to 1 s.f. so you can't really just say that εr = εr-1.

    Thanks.
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    well 2) is the polarisation current density and 1) is the displacement current density dD/dt

    so yer, the first one
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    Ah ok, thanks a lot
 
 
 
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Updated: January 27, 2010
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