This is messing with my head, Faraday Paradox !

[BrianHG]

   Why?  The fact that I am seeing DC voltage doesn't make things any better.

See video:

[RoGeorge]

The next one shows mechanical rotation instead of DC volts:

Arago's Scheibe,Disk (also see the YT video description)
xofunkox-scientific experiments


And if that was not confusing enough, see the Sagnac effect.  Or look at the humble gyroscope hanged from only one side while it is defying gravity.  Physics is all smoke and mirrors.  This Universe is playing tricks on us, and I know it does, yet I can't evade it. 

[BrianHG]

And if that was not confusing enough, see the Sagnac effect.  Or look at the humble gyroscope hanged from only one side while it is defying gravity.

Nothing confusing about those for me.  I can easily image the forces going on in my head...

  But that stupid magnet sitting on the wheel, not relatively moving, and it is still making DC even through the commutators shorted to 2 points on the disc... 

[ejeffrey]

Despite starting off with "it's still not understood to this day" it provides a pretty clear explanation in the second half of the video.  You have to consider the effect of the leads.

Providing the explanation two ways, once where the magnetic field is though to co-rotate with the magnet and the other without makes it more confusing that it needs to be, but if you pick one it's fine.  The choice is rather meaningless anyway.

[ejeffrey]

Also note that the bottom electrode goes to the axle, not the edge of the disc.

If you rotate the bottom electrode so that it passes under the top electrode, then shrink the magnet to only cover the area between the electodes it should be pretty clear what is happening.  The magnetic field in the rest of the disk is then irrelevant. 

[RoGeorge]

How about the Dzghanibekov effect?  No magnets and no wires, yet the the rotating object flips exactly 180 degrees back and forth.  That's not even smoke and wires, that's witchcraft. 

The Bizarre Behavior of Rotating Bodies
Veritasium


 

[T3sl4co1l]

A classic:

The original site has unfortunately gone offline, but it is archived here:
https://web.archive.org/web/20190409110824fw_/https://mysite.du.edu/~jcalvert/tech/faraday.htm

This is just one teaser of course, but the bulk of the related pages should introduce or indeed teach the solution to it; I found these pages quite readable and informative, even their use of equations easy to understand.

Tim

[RoGeorge]

A few more circular motion oddities:

The Most Mind-Blowing Aspect of Circular Motion (see it in slow motion at minute 11:10)
All Things Physics


Coriolis Effect (see it in slow motion at minute 00:50)
TSG Physics


8.01x - Lect 24 - Rolling Motion, Gyroscopes, VERY NON-INTUITIVE (see both demos, at minute 22:18 , and 35:15 )
Lectures by Walter Lewin. They will make you ♥ Physics.



The only reasonable explanation to all these is that the circular motion was one of those unbaked features, released without proper testing.  Later, all the reported bugs of physics were proclaimed features, and never to be fixed, so to not break the backwards compatibility for the time travelers. 

[rfeecs]

From here: https://www.feynmanlectures.caltech.edu/II_13.html

There is no way to make sense, in general, out of the idea of “the speed of a moving field line.” The fields are our way of describing what goes on at a point in space. In particular, E and B tell us about the forces that will act on a moving particle. The question “What is the force on a charge from a moving magnetic field?” doesn’t mean anything precise.

So forget saying "the magnetic field is moving".

In both cases, whether the magnet is rotating or not, the magnetic field at each point (x,y,z) in space is the same.

So all that matters is the free charge that is moving through the field.

He pretty much said this at the end of the video.

[RoGeorge]

https://www.feynmanlectures.caltech.edu/II_13.html

That reminds me of a guy from India, teaching in a very intuitive way the Maxwell's equations as if he was at the Feynman lectures about electromagnetism, and asking Feynman directly. 

Maxwell's equations are intuitive! (Ep: 1 - Power of Gauss's Law)
FloatHeadPhysics


Maxwell's equation explained logically! (Ep 2: Faraday's law powers the world)
FloatHeadPhysics

[EPAIII]

I watched that first video because, in spite of a degree in physics, I had never heard of the "Faraday Paradox". That's 9:20 that I will never get back.

It is only a paradox if you don't understand that you must consider the entire circuit and not just focus on one part of it. It is CLICK BAIT! Nothing more. No serious physicist would waste any time on it.

It is in the same league as those math problems that "everybody gets wrong".

[Circlotron]

I did a *lot* of thinking about this back in 2002. I came up with a flow chart that seems to lead to some awkward conclusions. If there are some wrong conclusions in it I'd like to know.

[BrianHG]

I did a *lot* of thinking about this back in 2002. I came up with a flow chart that seems to lead to some awkward conclusions. If there are some wrong conclusions in it I'd like to know.

LOL, nice logic puzzle.

Looking at the 'Arago's Scheibe Disk' helps: ASD

[EPAIII]

Without seeing the exact apparatus that you are talking about it is difficult to say anything.

I did a *lot* of thinking about this back in 2002. I came up with a flow chart that seems to lead to some awkward conclusions. If there are some wrong conclusions in it I'd like to know.