Talk:Kirchhoff's laws

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The title should be "Kirchoff's Laws": there are two of them, almost invariably cited together.

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I agree. --Ed Poor

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And, according to Googling, it's "Kirchhoff" with two h's, so I'm moving it again! The Anome

An anonymous user (130.225.29.254) added a note about displacement current, which I expanded and moved to the capacitor article. I'm not sure if the concept belongs in this article, since I assume that K's circuit laws apply only to DC or steady-state AC analysis. I don't think the term displacement current belongs in this article, because it's an obsolete concoction that went out with ether theory, but some explanation of how (if at all) to apply the laws to capacitors and inductors might be useful. -- Heron 14:34, 26 Mar 2004 (UTC)

Displacement current is not an obsolete concept. It is simply dD/dt, and is not tied to ether theory. And the person's change was absolutely correct. In terms of Maxwell's equations, Kirchhoff's current law is equivalent to $\nabla \cdot \mathbf {J} =0$, which is true only when charge is not building up anywhere ($d\rho /dt=0$). That isn't the case in a capacitor, but you can fix it by using Maxwell's correction to Ampere's law: $\nabla \cdot (\mathbf {J} +d\mathbf {D} /dt)=0$ always. I'll try to modify the article to include this general statement. —Steven G. Johnson 19:35, Mar 26, 2004 (UTC)

Thanks, Steven. I stand corrected. I look forward to reading the amended version. -- Heron 21:16, 26 Mar 2004 (UTC) Oh, and thanks for sorting out my edit in the capacitor article, too. -- Heron 21:22, 26 Mar 2004 (UTC)