Recent content by burashka

Yes, they would. But add also friction (resistance) and they would, on average, attain a constant drift velocity. Yes, the total momentum of matter+field is always conserved. But you need to consider radiation to see how this works. Perhaps that was what you meant by "acting on magnetic...

I thought we've discussed this. This is purely a matter of terminology. I have explained that when physicists say, for example, "electric filed does work" they imply the more precise statement that the force qE does work. When they say that MF does no work, they imply that the force (q/c)vxB...

I am a little confused. There is no centripetal force in the lab frame; only the Lorentz force. The really-really total momentum is, of course, always conserved, but to see that you need to account for the momentum of the cyclotron radiation. As for the mechanical system only, its momentum does...

Yes, exactly, the third law follows from conservation of momentum. Momentum is conserved in every pair-wise collision. However, the magnetic field does change the momentum of freely moving charged particles 9the conductivity electrons) inbetween the collisions. This is why, I think, the third...

Unfortunately, it won't. The mathematical expression for the Lorenz force has explicitly a charge or a charge density in it (if we use the expression for the force density). Expressions which contain currents, say J, are based on the assumption that J=rho*v, where rho is the charge density. See...

I am not sure about Spinoza and emotions, all this is totally above my pay scale. But one thing seems to be certain. There is a big difference between "untested" and "untestable" and the great lesson that Galileo has taught us is that we should not spend energy thinking about things or theories...

See this: author = "Assis, A. K. T. and Rodrigues, W. A. and Mania, A. J.", title = "The electric field outside a stationary resistive wire carrying a constant current", journal = "Foundations of Physics", year = 1999, volume = 29, number = 5, pages...

At any rate, there is no need to shout or be impolite. Of course I understood your argument the first time I saw it. I've heard it many times before from students. You should not assume that you are the first to come up with this great counterexample. The Lorenz Force on a point particle of...

I have read some of the posts in this thread but not all. However, it appears to me that some important but rather elementary facts are being lost sight of. First, an electric wire is made of charged particles. When these particles move, as the wire moves as a whole, there might be some work...

Yes, exactly. In fact, most of the energy goes straight to radiation. I think I have said previously "visible and otherwise". Of course, we consider here the filament only. For the tiny wire that heats up inside the bulb, the mechanisms of heat transfer related to heat diffusion and convection...

And where does the heat go, do you suppose?

When you turn on a lignt bulb, where do you think those 100Watts go? Let's presume that we're talking HID lighting, among the most efficient in current use. E=I/R (Ohm's law) gets us on the right track. Most of the energy, alas, goes straight to ground. Only about 2.5% is emitted as...

That lagrangian you wrote down is not the related to the system I'm describing. You have charges in there, but there is nothing charged here. The magnet and the iron are both neutral. Any macroscopic object is made up of electrons, protons ane neutrons. Except for neutrons, these are...

You don't have to consider the final state to be after the collision. You can if you want, but energy is conserved <i>at all times</i> so I can pick any initial and final times that I want. When the magnets attract each other, there is an increase in kinetic energy. I'm interested in...