Ah, you’re thinking of classic scams. In most modern crackpot scams, instead the con artist just keeps the scam going forever. This new trick seems to have been discovered around 1980, and several groups have used it.
Remember, there’s a vast population out there who are waiting for you to jump ship to Argentina. If you never do so …why, that’s proof it wasn’t a con game! Thousands of previously skeptical people will now wish to invest. And don’t forget that you can draw an enormous salary for all the decades that you keep the game going. You’ll end up with far more income than if you’d just run off with the money.
All electric motors are generators. Every one of them. Electric motors rotate due to an magnetic interaction between the rotor (rotating part), and the stator (stationary part). In the simplest machine, a DC motor, the stator can be permanent magnets mounted to the motor case. The rotor is called an armature, and is connected to a power source through a commutator… Essentially a rotating switch, that applies and removes power to sections of the armature, magnetizing certain sections.
A section is magnetized as it approaches the stator magnets, so it is attracted to them, and the magnetizing current is switched off as it passes the magnet (so as not to generate reverse torque).
BUT any conductor moving through a magnetic field also generates electricity. In the case of the DC machine, the amount of this “Counter EMF” generated will always be almost exactly the voltage as is applied to the armature by the power source. If there were no counter EMF generated, the motor armature would appear to be a dead short to the power source. This is one reason that motors (directly powered, not through a speed control device) take so much current to start, but (if the shaft is uncoupled from a load) very little to run. During the startup phase, the motor goes from appearing to be almost a dead short, with only the current/winding resistance losses to limit the current. As it speeds up, the CEMF increases, until it matches the applied forward EMF. This is also an explanation as to how a DC (or Universal - typically found in power tools) motor can vary in speed, and operate at different speeds. The final speed (ignoring loading for now) is only dependent on the supplied voltage, and the magnetic structure of the motor.
The thing is, as long as there is even a very weak magnetic field differential between the stator and the rotor (which must be present, or it would never spin), the motor is going to try it’s darndest to speed up to generate enough CEMF to match the applied forward EMF. The weaker the field differential is, the faster the rotor will spin to try to accomplish that balance.
If the CEMF were actually eliminated, the rotor would attempt to spin to destructive speeds (something that actually does happen fairly often on DC motors with shunt-wound field (stator) coils).
AC machines do not have the runaway problem that DC machines do, as their speed is based on the number of magnetic poles in the motor, and the applied frequency. The CEMF interaction though still exists, and is required in order for an AC motor to not appear as a dead short to its power source.
— I tried to make that description sort of simplistic, motor theory is actually surprisingly complex for how simple the machines actually are.
Congratulations, Khendrask, that airy, windy sound you just heard was made by **MOIDALIZE’s **post doing a low pass just above your cranium. Ain’t you glad you just typed about 500 words as a serious response?
Hey, be nice to the newbie with technical smarts. We need all we can get.
And Khendrask, I appreciated your post. I’m a scientist not an engineer. Motors are magic boxes to me.
The kinetic energy of the clay ball is not conserved. In order to fulfill conservation of energy in that case, we have to invoke new interactions to explain where the energy went. (I try to explain things at an introductory level whenever possible.)
It’s naturally confusing why we have irreversible processes when all the individual interactions are reversible. At the simplest level, it’s because there’re many ways to have disorder and only a few ways to have order.
Think of a bowl of water with a drop of dye. The dye molecules reversibly swap places with nearby water molecules. Look at a molecule of dye on the boundary. It swaps places with the water it’s next to. At the next moment in time, the dye could switch back to it’s originally location. But it’s equally likely to swap places with one of the other water molecules that are farther from the original position. And the odds are the it will switch with one of those.
All those odds, for all those dye molecules, add up to the dye diffusing out into the water. Sure, it’s possible that the dye could all concentrate back up in one spot. But there’s many more ways for the dye to be diffuse. So that’s what we observe.
That’s how reversible (and energy conserving) interactions can accumulate into non-reversible net effects.
So they must make it out of unobtainium.
I’m convinced! Now the only question is if I need to convert my check from dollars to pounds in order to invest.
That’s actually a fair point - and certainly now - I concede.
Earlier in the game, though, they were all about “Ooh! We’ve measured an effect that looks like something a bit weird”, which back then (before the farcical demo) appeared not completely against the grain.
