This seems more geared toward making the teacher sound smart than teaching the student. More formal than informal, expecting the audience to just comprehend what you're trying to say. Overall though I did learn some stuff (like that inverse square proportionality) and the animations were especially helpful.
At high frequencies, will there be a difference between a solid metal bar inside the solenoid and a metal pipe with some thickness? seeing that skin effect isolates the magnetic field at the surface of the metal bar
Possibly because the title is "skin effect visualized", and it then starts off with a purely math based description, and I can't play it at 2x speed, like I need to for most complex topics to not get distracted (if only I knew about this trick back in school...), because his pronunciation combined with the microphone setup makes it very muddled.
When you show the field vector plots (at time 0:25 for example), the right side of the visualization looks correct, but the left side confuses me as the arrows point in a non-intuitive way compared to the flux lines. What am I missing?
Hello hi, thanks for the beautiful explanation. Can you please suggest me a source where I can find the derivations of the modified Maxwell's eqns you have shown at 2:54?
Can't really pinpoint a single source since I took it from the software and that is their way of description used in that particular physics module. However, I can comment on how they differ from Maxwell's equations in default form differential form you see for example in wikipedia. 1) This is Ampère's circuital law. Term for displacment currents is ignored. Relation B= mu H is used. 2) This is mathematical way of experssing magnetic field with a "magnetic vector potential" A. It is an anolog of what eletric potential is to Electric field. In short it is more convienient way for some calculation to use Magnetic vector potential. 3) That is Ohm's law in differential form and a harmonic approximation with complex numbers is used for alternating magnetic field. 4) Here again vectorpotential expression is used. Doing that electric field becomes E=-(grad phi + partial time derivative of A). The first part is ignored and the second part is what we see on the screen when we do the time derivative of a harmonic function expressed with complex numbers.
One thing I never understood about the skin effect is why the induction current follows the incidental current. I would think when the current reaches a maximum, the magnetic field stops changing so the skin effect should be eliminated. Then, as the magnetic field begins to change again, as the current reduces, the skin effect would flip and become the core effect. Then when the current reaches 0, the skin/core effect would be at its maximum.
The resulting animations you see here are time-averaged solutions. That means that the result is a static picture and the direction of the magnetic field is chosen arbitrary (in this case by default up). Things move in animations because I change frequency so there are a lot of static pictures that are slightly different. Your question could be answered with calculations and animation where time is changed. In 0:30 there is such animation but without conductor inside. To get such animation one should do the transient calculation ( more difficult than frequency-domain used here) and there you could really see how magnetic field changes outside and inside the conductor. Only then we could observe things you mentioned that happen within a period of one oscillation. Like how magnetic field inside conductor lags behind applied field outside.
So "skin effect" is theoretically because the surface electrons can flip their magnetic moments into alignment faster than electrons in atoms in center of the wire?
I was hoping this would go into more detail regarding the generation of back EMF due to eddy currents formed by the changing current and resulting change in the internal field of the work piece
Next one will be demonstration of induction heating, melting and levitation. (I have already filmed the footage.) After that it is still undecided. In principle I do have plans to do something with actual MHD - first it might be conduction pump of liquid metal or Hartmann flow.
Hi, I have a question regarding the skin effect of induction heating, is it possible to heating a non magnetic material? Such as aluminum, titanium, etc
Yes, it is possible to heat all metals with induction heating ( and some nonmetals as well, e.g graphite). In another video, we show exactly aluminum melting and copper heating.
@@MHDTechnologyLaboratory well, do you know how to prevent an induction effect on the bolt of Stainless steel, I have an induction heating for a galvanizing application, I increased the temp proportional to the current, is it possible to heating the surrounding such as bolts?
@@MHDTechnologyLaboratory Thank you for your response. I have an additional question. Why do people talk about skin effect as the concentration of electrons in a wire in an AC signal?
@@somerandomguy4607 I think that is the most common case where the effect can be found. Plus it has the immediate impact of changing the electrical resistance of the wire. Also, it is easier to sketch and explain, because you can do it in 2D example of cross-section of wire.
