Talk:Electric susceptibility

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Isn't this just the low velocity approximation?

Isn't it less pleasant in relativstic materials? I've encountered mention that D = \epsilon_0 E + P is a nonrelativistic limit. Isn't the full expression something like D = \epsilon_0 E + P + (1/c) [(v/c) x M] where x is the cross product? I seem to recall if you try and eliminate M and P from the expressions for D and H you end up with an infinte series in increasing powers of gamma squared, where gamma is as it usually is in special relativity i.e. gamma = 1/ sqrt{1-v^2/c^2)

Counterpart for H is H = B/mu_0 - M + c [(v/c) x P]

what is it?

I would say that susceptibility measures how polarizable a dielectric medium is. How susceptible it is to being polarized by an electric field. The greater the susceptibility/polarizability, the more useful it is for making large-value capacitors. Or, you could say, when a material is used to make a capacitor, the greater the susceptibility, the greater the capacitance. Something like that.

Pfalstad 19:52, 2 January 2006 (UTC)[reply]

Thanks, Paul. I'll work something out along those lines,--Light current 20:42, 2 January 2006 (UTC)[reply]

change log

Mostly just reworded a few things. eg removed the phrase "makes the integral disappear" as the language was a bit causual. The integral hasn't disapeared, we have changed the basis!

Also changed the phrasing of dispersion properties. Do people think a reference to group velocity is required? Also I think there might be too much of a seperation between susceptibility and relative permiability, it might be confusing. They walk hand in hand. Although you dont want people thinking they are the same object, they do differ by unity! Timwilson85 18:00, 21 September 2007 (UTC)[reply]