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Energy doesn't FLOW the way you THINK! (Electrodynamics)

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Swend

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Hi friends

It seems to me that fundamental electric theory is no longer taught in school, which is a shame as it results in everyone having their own intuition and interpretation about it, leading to silly and time wasting discussions which everyone would be better without.

In an attempt to rectify this, I have found a youtube video that discusses the Poynting Vector in a correct but rather youthful manner, I suggest that try to look past that and actually listen to what he says and illustrates.

Energy doesn't FLOW the way you THINK! (Electrodynamics)

Quoting from the introduction "Based on the laws of electrodynamics, energy cannot flow in the same direction as the electric current. According to the Poynting vector, electric power will flow anywhere there is both an electric field and a magnetic field. The consequences may surprise you."

A short recap of the video (SPOILER ALERT):
.
.
1. An electric circuit is not a closed system (system as in physics)
2. Current is not energy, it's merely a facilitator for transceiving energy.
3. An electric circuit transceives energy from the "field" or "vacuum" or "space" because Poynting says so.
 

andre_luis

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Each model of representation of a physical phenomen is appropriate to the school level in question. For example, quoting the Poynting vector makes sense only when the student is familiar with the Maxwell's equations in differential form, which postulates that varying one field generates another field, and vice versa, even since being the pointing vector a "vector product" of both fields, even the mathematics of this orthogonality is not trivial; by the way, at least in the undergraduate course I did, such a concept and associated math was properly introduced and explored. To reinforce this approach, I would also cite the fundamentals of chemistry: Although a deterministic concept is initially taught regarding the position of the electron in the orbital at the basic school levels, this seems to be appropriate at the time the subject is presented, and only afterwards is it corrected, demonstrating the probabilistic nature of the electron position.

In short, I consider it is appropriate to present a simplified concept at the outset, as this follows the same chronology of evolution of science as it was has unfolded, somehow reviving the questions raised and conclusions people had based on the so limited information available at the time.
 

Swend

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Each model of representation of a physical phenomen is appropriate to the school level in question. For example, quoting the Poynting vector makes sense only when the student is familiar with the Maxwell's equations in differential form, which postulates that varying one field generates another field, and vice versa, even since being the pointing vector a "vector product" of both fields, even the mathematics of this orthogonality is not trivial

I agree the mathematics is definitely not trivial, that's why it even more impressive that Nick Lucid (the video channel owner) still manages to covey the essence of such complex math only by the use of proper pedagogy. I know it is not in any way complete, but it is a extremely good starting point for someone that wishes to educated himself further.

by the way, at least in the undergraduate course I did, such a concept and associated math was properly introduced and explored. To reinforce this approach, I would also cite the fundamentals of chemistry: Although a deterministic concept is initially taught regarding the position of the electron in the orbital at the basic school levels, this seems to be appropriate at the time the subject is presented, and only afterwards is it corrected, demonstrating the probabilistic nature of the electron position.

Yes, but the problem with that is, that when you are presented with this initial information, the educator usually presents it as the whole truth (intentionally or not). If you are then not programmed to question things, "afterwards" may never happen and you are left with an individual with a personal intuition about the subject. I personally wasn't acquainted with Poynting until 20 years after I left college, so you were apparently one of the lucky ones that got a proper education.

In short, I consider it is appropriate to present a simplified concept at the outset, as this follows the same chronology of evolution of science as it was has unfolded, somehow reviving the questions raised and conclusions people had based on the so limited information available at the time.

Great, I was thinking, if someone took Nick Lucids videos in his electrodynamics series and transcribed them into document form, they could be used as a primer/reference e.g. here on edaboard. I wouldn't mind performing such a community service as it would also be beneficial for me personally.

Cheers.
 

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