Science Buddies: "Ask an Expert"

I'm doing a presentation this week about my electromagnetic motor. My independent variable was the size of the coil that spun in the motor, but I'm not sure how diameter effected the motor. Could someone please give me a site or explain this to me?

I'm not much of a EE, so I tried to look this up for you on the web without very much success (there are too many irrelevant results messing up the search).

So, fall back on science: what did your results show? It should be possible to determine the relationship from the data...

In any event, for a question like this, I think you might have better luck going to the library and finding a book on electric motor design... it's possible you might be able to learn something from http://www.electricmotors.machinedesign.com/ or http://www.engineersedge.com/motors/motor_menu.shtml or http://www.oddparts.com/acsi/motortut.htm .

Hmmm. what kind of electric motor was this? There are a lot of different types that have different calculations that seem to go with them.

Hope you still can use it,
This is a good diagram of the currents and such.
http://hyperphysics.phy-astr.gsu.edu/hb ... dc.html#c1

Here is a link that desribes the force on a current carrying coil from an externally applied magnetic field.

http://hyperphysics.phy-astr.gsu.edu/hbase/hframe.html

Let us assume your current was the same each time you changed the coil, you should assume this. The "torque" on your magnetic moment will depend on the area of the coil, and the external applied field. One thing that compilcates your procedure is that the magnetic field from the permanent magnets of your motor will drop off pretty quick ass the coil size decreases.

Did you compensate for this by keeping the distance from the magnets to the coil constant? If not thats ok, if you can explain all of this that will be good enough.

Hope it helps and is not too late.