This hurts my brain.

[Burgerman]

https://www.youtube.com/watch?v=bHIhgxav9LY

While I know this is true, as I study physics for fun for most of my life, i still dont get this.


youtu.be/bHIhgxav9LY

[snaker]

@BM: We all know an electric current is a flow of electrons. And those electrons go from the negative pole to the positive pole. Why in all electric/electronic diagrams, the current's direction is drawn from positive pole to negative pole? This confused me in a long time, since I was a pupil. I asked teachers of physics but nobody gave me a clear answer. In fact, they did not know neither. I just found the answer some year ago by chance. I am curious in the West, how pupils are taught in physics. If teachers of physics in UK are asked that question above, do all of them know the answer?

[Burgerman]

Depends on what level these teachers are. At school, I doubt it. Or rather they know the facts, and that its really all about fields. But nobody thinks about it that way. Unless theres no wire... Like radio or light.

We know it is true because otherwise a transformer wouldnt work... Or a motor.

As for direction of electron flow, we are all taught in school that it flows the opposite way to the convention of plus/minus but that since everyone agrees that it doesent matter. Originally they didnt know so got it wrong. Too late to change.

Energy outside of the wire...

https://www.wheelchairdriver.com/gopro/ ... -state.mp4

[snaker]

I meant my question about the current direction (not the video). What is your answer? Can all teachers of physics in UK answer it?

We all know an electric current is a flow of electrons. And those electrons go from the negative pole to the positive pole. Why in all electric/electronic diagrams, the current's direction is drawn from positive pole to negative pole?

[Burgerman]

Yes. We are all taught that at around 13 years old.

[Burgerman]

Regarding the video, it must be correct or this wouldnt work! Sun power.

I posted the wrong vid above... It said current state in the name so I thought it was this! (correct vid) here: https://www.wheelchairdriver.com/gopro/magic.mp4

Its interesting anyway to see all my junk. https://www.wheelchairdriver.com/gopro/ ... -state.mp4

Or this https://www.wheelchairdriver.com/gopro/magnet2.mp4

Or this: https://www.wheelchairdriver.com/gopro/magnetic.mp4

[snaker]

Yes, the answer is simply "Too late to change". So all 13 years old kids in UK know it. I doubt any teacher in physics in VN can. That makes a big difference between UK vs VN.

[Burgerman]

I doubt more than 10% kids would know it as they are not absorbing this stuff. I did, most wont.

[LROBBINS]

That video about fields left out one thing that I think makes it easier to understand. The current flowing in the wire produces an electromagnetic field that transfers energy - yes. BUT for the light bulb to light that requires movement of electrons inside its filament, which happens because the filament is acting as one winding of a transformer that's absorbing the energy transmitted by the external field.

[Burgerman]

Yes. Its still an odd way to think about it when used to working with electrics to me though!

What about my demonstrations?
Or this https://www.wheelchairdriver.com/gopro/magnet2.mp4
Or this: https://www.wheelchairdriver.com/gopro/magnetic.mp4

Those show this happening. In one case in reverse!

[LROBBINS]

I don't understand that first video - what's the source of the field, and which motion are you talking about.

The second one is pretty clear, but could also use some explanation along with the picture. The source of the field is clear: a coil of wire connected to a power supply, I assume DC. Movement of the steel disc in that field generates eddy currents in the disc that produce their own magnetic field that interacts with the coil. But one can't see the eddy currents the same way you can see a light bulb filament get hot, so it looks even more like magic.

[Burgerman]

The first vid demonstrates the electrical current in the wire (the non magnetic, alloy tube in this case as eddy currents) is generated FROM fields. And the EMF slows the magnet. So gravity causes the magnet to heat up the tube. The power came from the field.

The 2nd one is the opposite. The electrons flow from the power supply through that bundle of wire but the energy is outside of the wire. And it moves the magnet.