I was reading about green energy the other day when I heard about some “free energy” stuff somehow based on magnetism. The interesting thing was that many people – including one professional electrician – claimed that it actually worked, while others said that it is a violation of the laws of physics and a scam. Of course I had to investigate. It was… interesting.
The so-called “Johnson Motor” (US Patent # 4,151,431, issued April 24, 1979) is quite ingenious. Basically it has two concentric rings of permanent magnets, inner ring rotating with respect to the other. The magic is in the form of the magnets: on the outer ring they are slightly lens-like, focusing magnetic flux on one side of them, while in the inner all the N-poles were directed outwards.
At the time it was invented it apparently was a bit unclear how it actually worked. For one thing, there’s the conventional wisdom that magnets don’t do any work. This is a false generalization. It also seemed to create mechanical energy out of thin air. Alas, it does not. But a fact is that the thing did work, because it was only patented after Johnson had carried a working prototype to the office. Now let’s look at these misunderstandings.
Magnets do work
Physic’s teachers keep claiming that magnets don’t really do work. This is true if we are working with particles with no magnetic momentum of their own. Say a copper wire. If it moves through a magnetic field, the field will do work on electrons on that wire, inducing current. If the wire is a coil, the electrons can’t escape it and the wire itself may be affected by a work of those electrons do against it, but still magnetism itself does not affect the wire directly.
However, for particles that have some magnetic momentum, like electrons, this is not true. In a magnetic field they have magnetic potential energy. (Just like in gravitational field all particles with rest mass have potential energy.) Any change in this potential energy amounts to work. This work is responsible for inducing current in the example above.
And here comes the surprise: magnetic materials (like iron) have intrinsic magnetic momentum! A common piece of iron is just a bunch of magnets each pointing in a different direction and canceling others out. A simple household magnet is a piece of iron that has had its magnets brought into alignment, pointing in the same direction. When you pick a screw from the table with a tip of a magnetized screwdriver, what happens is that a strong magnetic field of aligned small magnets meets a myriad of weak magnetic fields – and attracts some of these, repelling others, turning those atoms “around”, aligning the magnets. It actually magnetizes the screw a bit to make the connection stronger. (On the other hand, the magnets in the screw do some work on the screwdriver misaligning its magnets slightly.)
Thus, when an object with a magnetic field of its own encounters another magnetic field, these fields will interact, potential energy will transfer and work will be done. Magnetic fields do work against permanent magnets. And it is this work that rotates the Johnson motor.
Mike Weissman has given a slightly more insight to this issue.
The Johnson Motor conserves energy
I don’ t know who came up with the idea that it doesn’t. It was ingenious – or off the beaten track – in not using a fluid to wind a turbine. Think about its: coal, gas, nuclear: all are basically boiling water to run through a turbine. Dams and windmills: turbine. Photovoltaic cells are the only different technology, but they produce electricity, not movement. So here we have a motor that doesn’t take any fuel, produces no toxic emissions, doesn’t need anything to wind a turbine, but still does some useful work? Theoretically impossible. Is it?
It is. But that’s not what’s happening in the Johnson motor – it does use “fuel”: permanent magnets. First we’ll need to understand slightly better the complex magnetic forces in the Johnson motor. Jean-Louis Naudin modeled them and explained how the stuff works, but here’s a brief.
The key is that the magnets are not symmetrical. Rather they are carefully imbalanced in a way that in one way or another they are always falling to one direction, say left. So it takes a step left to stay upright – just to find that the magnetic field it was reaching keeps curving and it needs to take another step. On the whole, the motor a wall of magnetic fields curving into a loop, with the rotor falling ever forward just to lean on it.
Now the magnetic fields there are complex, but the bottom line is that they do work: attract and repel each other. While on macro-level this results in rotary motion, on a molecular level it amounts to little atoms pushing and pulling each other out of configuration – or magnetic misalignment. In plain words, the magnets slowly lose their magnetic strength.
It is difficult to compare the efficiency of Johnson motor with that of a diesel generator. How do you know how much energy is there in the construction machine? The only way is to take it all out. Still its like comparing apples and oranges. There are some things that seem clear, however.
1) In small scale it’s relatively cheap. People have reported of having cut down their electric bills enough to have paid back for the investment in a matter of months.
2) It’s more efficient than combustion based power. In combustion something needs to be burned to gain chemical energy, which is then transformed into linear mechanical energy, and further into rotary. Magnetic energy doesn’t even bother with the chemical.
3) It’s a grossly inefficient design. Johnson motor in the form it was patented is a proof of concept kind of thing. There are later adaptations, but they all suffer from being bulky and inefficient by design – they have not been perfected by engineering. There’s a new generation technology coming, utilizing similar principles, but on a whole new level: one where stuff can actually be engineered.
Believe it or nuts: It works, if you can make it work.