Can The Faraday Paradox Be Solved?

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[TheActionLab]

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[deusexaethera]

Spinning the magnet and the disc together still produces a voltage because OTHER parts of the circuit are stationary. There is still relative motion between the magnet and the circuit, just not between the magnet and the disc specifically. If you put the entire apparatus on a turntable, then you will get no voltage, as expected.

As for why the spinning magnet doesn't produce a voltage, actually it does -- but it produces the SAME voltage on both sides of the circuit. If you connected two multimeters to the circuit, one on each side, with a ground connection in the middle, you would see identical voltage readouts on both multimeters.

[travisholt]

Only 60 seconds in and already understand how generators/motors work. 🎉 Phenomenal

[ppsicop]

The shot you use that shows the scientists talking about something was very helpful to illustrate the concept of scientists discussing science.

[Catman_]

I think the description that magnetic field lines is just a construct make the most sense to me. An electromagnetic field is literally just described with the polarity and strength of a section of the field, and any "lines" just outline areas where the strength is the same, kind of like a pressure or temperature map.

[Tsopni]

Please solve Fermi's Paradox next :)

[bitzblits]

Here's the next experiment you need to do: The same spinning disk but your closing wires run parallel to the magnetic field (i.e. Straight up and down), so they don't cut through the field lines.

[aboriani]

One thing I love about this channel is how unceremoniously the videos ends.

[snaplash]

Your disc magnet has north / south poles on it's faces, and the field lines are concentrated around the edge by the steel cup it's mounted in. When the aluminum disc is rotating under it. it's cutting through the field as it passes by the edge of the magnet. When the magnet is rotating, the edge field is equal all around, so it's not cutting through the conductor, and not generating voltage. If you had a magnet disc with north and south poles alternating around one face, it would work.

[live_destin-]

*Dr Stone fans already knowing this information:* 🤓

[taboosaboo]

Now I understand, thank you for the demo. The circuit drags, then jumps, then drags again.

[kapilmeetsingh]

REALLY Really need more such videos, As a high school student, it's fascinating for me because I Have learnt about these topics in school and now I'm applying these concepts in this paradoxes which is very cool

[davidharley]

I think "cutting field lines" is a red herring. What induces a voltage is a change in flux through a closed circuit, whether the magnet producing that flux is rotating or not is irrelevant. Consider a single wire rotating from the axis. As it rotates past the brushes the enclosed area changes, and flux being field * area this results in the induced voltage. But this requires a finite width brush. In the limit of infinite wires and an infinitely thin brush you will still get a voltage but generate no current. To generate current you require a finite width brush.

[attrition]

It's neat that the part where you move a wire over the magnet to create charge is basically how electric guitar pickups work. Never thought of it at a larger scale for some reason.

[russ]

I tried this in college with two toroidal magnets out of speakers (same as you had with your drill) but I machined a brass disk mounted to a brass axle such that the two toroidal magnets were placed on either side of the disk and because the disk was only about an eighth of an inch thick, the natural magnetic attraction of the two magnets clamped and rotated with the disk. I then put a multimeter from a brush on the outside edge of the disk and the axle and noted that in either case (whether magnet was held stationary or allowed to spin with the disk) a voltage was developed. I asked my physics professor and we never figured out what was going on. He referenced a very old book where the author claimed that the resolution lie in something to do with relativity (not around during Faraday). But I honestly never understood it sufficiently. I do remember the author claiming that if two equally charged particles a distance x apart were stationary then the force of repulsion was purely electrostatic. But if you as the observer were moving relative to the two particles, then the observed force between them was then a combination of electrostatic and magnetic because the motion gave rise to magnetic field around the charged particles.

I found your description excellent. Now subscribed.

[tsisqua]

And the movement of the wire across the magnet producing a charge is exactly how an electric guitar pickup works. When you pluck a metal string it moves back and forth over a copper-wound magnet which is grounded to the strings. The tiny electric charge is then amplified; the speed of the back and forth motion of the string electrically reproducing the pitch of the vibrating string.

[liam]

The plane of rotation is orthogonal to the field. When the metal is rotating, it is moving at right angles to the field, whether the magnet rotates of not.

[tomholroyd]

Very cool demonstration of an interesting effect! And as the professor said when the student complained that the result was counterintuitive, "When it comes to rotating invisible fields of force, you have no intuition"

[gabrieldehyrule]

An understanding of whether the field rotates or not delves deep into the relativistic origins of magnetic fields. Relativistic field transformation makes it so either the magnetic or electric field move the charges in either frame of reference, but you can also think of it like both fields being one and the same, a single field fulfilling the laws of special relativity

[DevinNeal-iluv]

I want to see more experiments.

1) the wire at the bottom: make it perpendicular to the disk itself by extending the disk holder, thus eliminating half of the wire from equation.
2) rotate a magnet above a wire.