Recent content by cmos

Just to elaborate on the last two posters, what your GRE guide is talking about is multipole moments. An accelerated charge actually acquires a dipole moment (maybe even higher-order moments depending on its motion), and hence radiates. I haven't looked at the problem in some time, but I could...

Yes. Sort of, but I think you might have the wrong idea. Specific frequencies will propagate, but these frequencies form a continuum ABOVE a certain cut-off frequency. The eigenvalues of the Helmholtz equation is the axial component of the wavevector (in engineering contexts this component...

This link could be useful.

If you define electrodynamics to be the study of matter with the electromagnetic field (i.e. with photons), then QED is simply a fully quantum-mechanical approach to that study. In that sense, the "standard QM rules" apply since what you're doing is simply applying QM to yet another problem...

chrisbaird, Your post (#22) is very similar to my post (#18); however, I like how you refer to the two divergence equations as "initial conditions" (perhaps "boundary conditions" would be a better term, but that's just semantics!). In this light, there seems to be a very important point...

When the solar cell is shorted, there is no external load and so no place external to the cell for there to be an IR drop. Hence, no power is externally delivered. Now in the case of an ammeter, an ideal ammeter is a device that draws no voltage (i.e. suffers no IR drop) but yet (somehow)...

If you had an infinitely long solenoid, then no, the experiment would not have the same result. Regardless of length, why do you assume the exterior B-field to be "very small?" If this were the case, then transformers wouldn't exist.

Why should the B-field be zero outside the solenoid? You don't have an infinitely-long solenoid, do you?

Agreed with the above post. Actually, there are some good resources... undergraduate- (or even graduate-) level physics textbooks. Like the guys above said, you could probably pick up a few books in the major areas of physics and teach yourself. Of course, most people find it easier to learn...

From my point of view, four of the big areas in terms of lasers (although, there are more): 1) A laser that integrates well on a silicon platform. 2) Nanoscale lasers (e.g. with cavities smallar than the wavelength). 3) Lasers for EUV lithography. 4) THz lasers. You should note though that...

Picture a single acceptor atom (with it's associated hole) placed in the semiconductor latice. That picture is electrically neutral. Any movement of the holes (i.e. the valence-band electrons) is thus due to diffusion.

But there is also a large number of "empty" valence band states on the p-side (these are your holes); this is compared to the large number of filled valence band states on the n-side. Thus valence band electrons will diffuse from the n-side to the p-side in order to fill the empty states. Of...

Completely correct (excpet for the slight typo in the first parentheses :-p). This happy coincidence you speak of is commonly called the equivalence of inertial and gravitational mass; i.e. that the m appearing in Newton's Second Law is the same m that appears in Newton's Law of Universal...

I'm willing the bet that the amount of detail he gave is probably nothing compared to the amount of detail a specialist in anyone of those fields is required to know. I mean no disrespect to you, but the ocean may seem infinitely large if you've never left the shore. Also, the total...

You might also try Callen, "Thermodynamics and an Introduction to Thermostatistics." It's meant as a text for physics majors back when physics majors studied classical thermodynamics separately from stat. mech. That being said, I find this text to be very useful for and accessible to non-physicists.