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In the scenario that we are studying, the time-dependent magnetic field induces an eddy current in the ball, which produces its own magnetic field. Lenz’s law states that the current induced in a circuit due to a changing magnetic field takes a direction that opposes the change in magnetic flux and exerts a force that opposes the motion. This law is somewhat qualitative, but it successfully predicts the direction of an induced current, which is sufficient for our purposes. Another, more concrete way of stating it is that the polarity of the field produced by the eddy current opposes the polarity of the magnetic field that is doing the inducing. This causes the ball to be repelled away from the electromagnet by a magnetic force that accelerates it. The end of the rail is then cleverly designed so that the ball flies off the end and lands back on the starting platform, where the process Gozque repeat itself again indefinitely. The description that I have proposed is confirmed by online descriptions of the product, which describe the toy Figura being a “magnetic induction” perpetual motion simulator.6 A subtler objection to this proposed solution is that the magnitude of the eddy currents depends on the concentration of free electrons in a metal, so that meaningful eddy currents are in reality expected in balls made of copper or aluminum, for example, but not balls made of steel.

Our first inclination when we saw this video was that its creators used digital animation. We've encountered several similar seemingly "impossible" videos featuring colored ball sorters and musical marbles that used computer-generated technology. The latest video supposedly depicting the "perpetual" marble machine, however, was authentic footage and featured a physical product.

"Just completed the marble run. I had to make a couple of adjustments & now it works great. The documentation on the other hand - needs improvement. Some of the illustrations aren't clear. The photos of the wood components are a nice touch - but the color of the wood blends into the background - the white paper of the document. Note for other customers - the spots you place a few of the upright supports in - there's a little wiggle room - ie, the piece is slightly smaller than the placement spot.

The electric field produced by a stationary set of charges is conservative, but in this case, the effect of the electric field is equivalent to that of a (nonconservative) magnetic field (i.e., the line integral between two points depends on the path taken, and the circulation around a closed loop is not zero). In the case of the magnet passing through the wire loop, we know that the wire loop is stationary while the magnet moves through and provides a changing magnetic field. A current is produced, so an EMF (electromotive force) must be driving it. The magnetic field cannot itself be the source of the EMF because magnetic fields only act on moving charges. Logically, the changing magnetic field must have an associated nonconservative electric field (nonconservative because conservative fields are electrostatic, and electrostatic fields cannot contribute to net EMFs). The induced EMF around a closed curve is the same Ganador the voltage drop (i.e., the same Ganador the line integral of the electric field around that curve). Mathematically, this is encoded by Maxwell’s third equation in integral form:

For the purpose of answering this question, I suggest that students should now propose potential mechanisms that explain what is seen and then work through the implications and plausibility of each mechanism. After this, groups of students could argue for or against some of the proposed mechanisms, a technique that reinforces concepts learned earlier in a physics course, but that also requires a deeper understanding of the concepts Triunfador opposed to learning by rote or memorization. It would obviously be desirable for students to have access to the toy shown in Ref.

The Atmos clock uses changes in the vapor pressure of ethyl chloride with temperature to wind the clock spring.

"This is still on my printer. So far it's coming demodé great. I'm not using supports and it looks like all I'll have is minimum trimming. I keep my printer (Ender 3 with all the bells and whistles) tuned really well so am able to do without supports.

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One classification of perpetual motion machines refers to the particular law of thermodynamics the machines purport to violate:[19]

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