Not really academic for this board, in my opinion. As far as I know, there are two ways to induce a voltage in a coil from a magnetic field. One is by varying the flux passing through the coil over time (Faraday's Law). This is the principle behind the ubiquitous transformer. The other is the effect on a (free) charge moving in a magnetic field. I tried to explain this to Chester. To wit:
> Chester, when a charge moves through a magnetic field there is a force on it that is at right angles to both the magnetic field and its direction of motion. This is what causes the hall effect as charges in the wire respond to this force and pile up on one side. Similarly, if a copper wire is passed over the pole of a magnet, the electrons in the wire will pile up on one end of the wire causing a voltage in the wire. If a copper or aluminum washer is made to spin over the pole of a magnet a constant or dc voltage will be induced between the inside hole and the outside rim of the washer. Unfortunately there are problems trying to make practical use of this effect. For one thing, the voltage is small. I hope this helps.
This is the effect Troy was measuring. It can generate ac or dc voltages depending on the configuration. For instance, for Troy's experiment with the coil on edge:
>Most likely you would get a single negative or positive pulse of reduced amplitude. The reason for this is that the field of the magnet drops off quickly with distance and one side of the coil is farther away from the magnet. It will produce a voltage opposite in polarity to that of the close side but much weaker. Should be an easy experiment to do.
The alternator designs you find on this board work because of this effect.
