[thedoc (OP)]

This is about the simplest electric motor you can build, and is the same type as the first electric motor built by Michael Faraday

Read more about this kitchen science experiment.
[chapter podcast=1000635 track=14.03.04/Naked_Scientists_Show_14.03.04_1002036.mp3] Listen to the Experiment[/chapter] or [download as MP3]

[CliffordK]

A most extraordinary device.  I may have to try to make one.  It doesn't seem as if it should work if you have a constant current.  Is it possible that you briefly loose contact as the wire spins?

What would happen if you add an LED either above or below the battery, before connection to the copper wire?  Would it give you a flickering light?

[RD]

What would happen if you add an LED either above or below the battery, before connection to the copper wire?  Would it give you a flickering light?

IIRC you need more than the 1.5volts output of a single AA battery to light an LED,
Essentially no current would pass though the wire until the voltage exceeded the threshold for the LED (Vd) ...

 [ Invalid Attachment ]
http://en.wikipedia.org/wiki/Light-emitting_diode#Technology

[CliffordK]

One can always connect 2 batteries to get 3 volts or so, and the system should still work.  My question, however was whether the power connections was intermittent.  Wiring an oscilloscope into the circuit would also tell one the same thing with better resolution.

[annie123]

I was at science fair where every kid had been given something similar to this but the copper wire did not go to the bottom of them battery. The two ends of the M shaped wire (the point of the M was on top of the battery) were left free and the wire spun around. I tried it at the fair myself and it worked but when I tried it home the wire did not turn and so I looked it up to see that it was supposed to be connected which made sense. So why did it work without being connected at the fair?

[PmbPhy]

A most extraordinary device.  I may have to try to make one.  It doesn't seem as if it should work if you have a constant current.  Is it possible that you briefly loose contact as the wire spins?

What would happen if you add an LED either above or below the battery, before connection to the copper wire?  Would it give you a flickering light?

It's a very simple device and the physics itself is very different too. As the title of this thread indicates the motor is called a Homopolar Motor and is related to the homopolar generator. Wiki explains it at:
http://en.wikipedia.org/wiki/Homopolar_motor

The battery causes a current to flow in the wire. There must be a magnetic field present for it to work. The charges moving through the wires cause a force to be exerted on the wires thus causing the loop to rotate.