Rotating Magnetic Rings: Can Inner Ring Rotate?

[apkrishna1963]

large number of magnets attached to a fixed non magnetic circular ring. Another non magnetic smaller radius ring with equal number of magnets is taken. Here magnets are attached such a way that like polls of the magnets of bigger and smaller rings are facing each other. Due to repulsive force is there a possibility of inner ring begin to rotate? Please explain.

 

[BruceW]

I'd guess the inner ring would rotate (if it was given a nudge to start it going). Like how a maglev train works.
Although due to the set-up, your rings might be more likely to fall out of plane with each other, so there would probably need to be some kind of stabilising mechanism.
Also, I reckon the rings would be less stable if they were small, since the magnetic fields of different parts of the ring would overlap.

 

[BruceW]

I guess its possible, but would be tricky to make...

 

[rcgldr]

The inner ring would tend to orient itself so it's magnets were between the outer magnets to maximize the distance between opposing poles. There might be some oscillation until it stablized, but it wouldn't rotate on it's own.

Regarding a maglev train, it's effectively rotating all the inner or outer magnets. There are two basic types of techonology used. Both need an input power source (the engines) in order to accomplish this.

http://en.wikipedia.org/wiki/Maglev_(transport)#Technology