Recent content by Nate Wellington

I think I am trying to answer a more "fundamental" question than that, one that doesn't require the use of permeabilities, etc. David Griffiths states that magnetic fields can "do no work." It seems to me that: (1) if you have just two pure magnetic dipoles--electrons--the magnetic field...

I know this question has been beaten to death, but I haven't seen a response that clearly (to me) answers the following: 1. Magnetic fields *can do work* on intrinsic dipoles, right? (e.g. two electrons can do work on one another via their intrinsic spin). 2. Magnetic materials can do work on...

Thank you! I think this is a good response. That being said, I still have the following confusion. In semi-conductors, the Hall coefficient can have a positive or a negative sign, depending on whether the transport is dominated by electrons or holes. I am under the impression that they way you...

It seems like when an electron moves to a higher energy level, even within the same band (conduction), the empty state should be a hole. But, we are told that in metals, electrons are the charge carriers. Do I just misunderstand what holes are? Or what is going on here?

For the Gauss's law case, I am talking about a wire with a uniform charge density lambda, as you say. And I am talking about finding the field a distance $z$ radially away from the midpoint of the wire. This is defined and easily calculable $\int_{-l/2}^{l/2} \lambda z dx/(x^2+z^2)^{3/2}$

At the exact center of a finite wire (i.e. a distance, say $L/2$ from each end), why can I not apply Gauss's Law in integral form to find an EXACT solution for the electric field? At the center of the wire, $E$ is entirely radial, so it seems like I should be able to draw an infinitesimally...