12 replies to this topic

[Moolkye]

I think there is power in a magnet. Hence the force displayed when putting, rather, repelling two similar poles together.

Trains that hover without speed limitations. Why not make beds that hover over magnets. Or Shoes. Or, dare I say it, cars. Ture the power comsumption would be great. But I look at the earth, which they say is a form of a magnet. Gravity. But how does it work?
Any thoughts on the subject?

[moldboy]

Intresting idea, however magnetic trains require 3 magnetic forces, the one on the ground which makes it hover up isn't like the magnet in the earth. The earth's magnetic pole is stringest and stands at north and south, however the train magnets are like millions of bar magnets all stood up on one end, not one long magnet. THere is then also an alternating magnet field to pull the train along, but that's in the walls.
Another problem you might have is ballence, have you ever tryed to float one magnet untop of antoehr in the air? It can't be done without support. Also more magnets might just cause problems with electronic systems, and the works.

[gaurdro]

While yes there is energy stored in a magnetic field, it's impractical to use in most situations on a large scale. it would be cool but as of yet impractical.

A side note. we can store energy in a magnetic field through a type of electrical device called an inductor. it is typically a coil of wire(solenoid) or a torus of wire (toroid) and have all sorts of uses but that gets into some deep physics and i'll refrain from posting that until it is requested.

[matto]

And if you have trains or people hovering, you would have to have a force which holds them in one place as well, not just one that keeps them above the ground because then they would be able to fly around with hardly any friction... which would be fun but... no.

It is an interesting idea, though. I think that I have heard similar ideas proposed before... sort of like automating traffic and using magnets and computers to control where people go and keep track of where they are and stuff. You wouldn't have to drive anymore, and in theory there would be no crashes. But I'm not sure how that would be implimented, and how "bugs" in the system will be reacted to, and how people would feel without actually being in control of where they are going.

[Avalon]

I have often wondered about using permanent magnets in a motor. The whole theory of an electric motor is that it uses magnetic force to make it rotate. Originally there were 2 electro-magnets used, one that rotates and one that is stationary. The stationary magnet 'pushes' the rotating magnet around, the speed of the motor is determined by the strength of the magnets. Newer motors now use a permanent magnet for the stationary magnet and vary the strength of the rotating magnet to control the speed. These motors are much smaller and energy efficient than the older motors.

Why can't we use 2 permanent magnets in a motor? I know the speed control would be difficult, but I'm sure with some engineering it could be overcome. (perhaps vary the distance between the rotating and stationary magnets?) A motor such as this would not consume any power and should be able to keep rotating for the life of the magnet, which is something like 400 years and produce no pollution. Seems to me this would be a very efficient motor and could really improve our energy comsumption and pollution problems.

Edited by Avalon, 24 May 2006 - 11:08 AM.

[Reaper]

That is a really interesting idea but the best thing of all is that this stuff could be possible in the near future !!!!!!!!!!!!!

[Cerebral Stasis]

The reason is because a two "perminant" magnets means the engine would never be able to be stopped, and furthermore, the energy used by the magnet would wear it down fast enough for it not to be practical. There's no such thing as free energy, there will always have to be some kind of fuel, so that means that having something work without any energy input is impossible.

Oh, and gravity isn't the same thing as magnetism. There are many non-magnetic bodies that also have a gravitational field. Heck, we humans have gravitational fields, they're just too small to do much.

[moldboy]

Quote

Why can't we use 2 permanent magnets in a motor?

one reason was already given, and I know you can solve the not being able to easystop with some sort of gear and clutch system, but the real reason motors aren't build with 2 permanant magnets is because they would never start spinning in the first place!. An electric motor spins when the magnet inside the motor attached to crank shaft (electromagnet) is in same polarity as the magnet on the outside. You are aware that the north ends of two diffrent magnets won't come together on their own accord, similarly the north end of one magnet won't become unattached from the south end of another magnet on it's own accord. Inside the motor the electro magnet is changing polarity as the motor spins, this generates the spin, how about a diagram:
N = permanat magnet North end
S = permanat magnet South end
n = electro north end
s = electro south end
+ = the crank shaft

in a stationary electric motor (one without power) the permanant magnets are holding the electro magnets (which is just a chunk of iron) in place:
|N| - + - |S| the "-" is the nonmagnetized iron, when you apply power the iron becomes chagred as:
|N| n + s |S| now remember how two north ends will repel each other? This force pushes the n and s away, however because they are attached to a center they spin rather then just shot straigh away, then just as the shaft turns the polarity of the magnet changes and the process is repeated on the other side. Now the motor in the diagram isn't that practical because to much motion would shake it off its path so there are more |N| and |S| pols areound the edge.

Hope that's understandable, it makes sense to me anyway.

Edited by moldboy, 24 May 2006 - 10:30 PM.

[Cerebral Stasis]

I'll admit my knowledge of engines is severely limited, so thanks for clearing that up, Moldboy.

[Wolves]

A motor, as stated above, will not function on 'permanent magnets' and I would like to explain exactly why, by explaining how a motor works in the first place.

Ok, so as you know, a motor functions mainly on magnets, but two different kinds of magnets.

A motor rotates due to attractive and repelling forces within it, this is all done with an electromagnet.
Some key terms for magnets:

Electromagnets, Armature, Commutator, Brushes and Field magnet.

Ok, as you know a motor spins when you apply power to it. But how is this accomplished you might ask? Well, inside a motor, there is two magnets, a typical magnet (the field magnet) and an electromagnet. The electromagnet has opposite forces of the field magnet at all times. This is all accomplished by the commutator. The comutator is a little piece within a magnet that reverses the current to the electromagnet when it spins to a certain point. When the forces are reversed, the electromagnet repels the field magnet's force and spins away from it, when it gets to that point again, the commutator reverses the current yet again and the electromagnet turns to repel from it, again. That is the most basic explanation I could write, but I'd reccommend reading up on them here at How Stuff Works:

[LINK]