Recent content by carllacan

Oh, I see. I was considering the coil as a coil, but I was using the word antenna because at the end of the day it is something that emits EM waves. I suppose they are actually different things, then.

Reasonings that compare sizes of antennas and wavelengths always confuse me a little. I know wavelength is important in waveguide theory and diffraction, but I don't see how it relates to antennas (maybe it's very basic, but I haven't studied antenna theory yet). I mean, my antenna is a coil...

Thank you all for your answers. I will try what you proposed as soon as I can.

Yes. A function generator plus an audio amplifier plus an antenna. I made a sweep between 20 Hz and 200 kHz while I measured currents, and noticed a peak at around 1 kHz (1.2 kHz, actually).

@jim hardy Thank you very much for your input. For the sake of simplicity I ignored Faraday's law and used the current equations. I hoped there would be a clear-cut answer for this problem, but I see I was being naive. In any case the question I was interested in was whether it is possible, in...

I have run a number of experiments, but none has shed any light on the matter. I have this set of three 2-winding transformers side-by-side, and when I apply a 1 kHz field on them the current through their windings increases, independent of other currents. The transformer directly under the...

No, for the moment I'm working with a simple model with just two solenoids side by side. I guess you mean that even if it doesn't induce any currents it can still saturate the core and reduce the output current, correct? That's an interesting possibility. However I am more interested in finding...

What happens to the current through a transformer windings if the whole system is under a uniform magnetic field in the direction of the coils and with frequency equal to that of the AC in current? I think the current induced in the primary solenoid should generate a field that would make up...

Ok, so the parameter of the transformation doesn't end up bein the coupling constant then?

Then there's some detail I misunderstood. To me the local phase symmetry ψ → ψeiq gives rise to a conserved current eψ*γ0γμ ψ, and when we use that current to couple the Dirac field to the EM field the parameter e plays the role of coupling constant. Did I get that wrong?

I understand what we classically know as the charge of a particle is actually the parameter of the local phase symmetry of the field the particle belongs to, the Noether current of which permits its coupling to the electromagnetic field. But when a field has phase symmetry it is symmetric under...

Yes, I was working with the Dirac equation.

Ok, so what about QFT? Would the answer depend on which fields ∂μ is acting on? Now that I think about it I'm not sure how the scalar product is defined in QFT. Is it the same as in non-relativistic QM?

I'm sorry if it is a silly question, but I've looked elsewhere and I haven't found the answer. Please tell me if any of the following is true: ∂μ† = -∂μ ∂i† = -∂i ∂μ† = -∂μ ∂i† = -∂i I'm studying QFT and I don't know how to proceed when I have to take the adjoint of a derivative. Sometimes it...

No, I don't see anything wrong or weird with the math. It is just that I found it curious that the Dirac field obeyed the equation for the scalar real field, and I though there might be some interesting physics behind the fact, like fermions and scalar real particles having some common property...