AC induction motors and eddy currents (1 Viewer)

[hectic18]

Hello

This refers to the dot point

Students: perform an investigation to demonstrate the principle of an AC induction motor

I've done basically the same prac as shown here http://hsc.csu.edu.au/physics/core/motors/2698/Phy935net.htm#net2 , but instead we turned a magnet blue-tacked onto a stirring rod lol :rofl:

What I don't understand is how the disc rotates in the same way as the magnet is rotated.

<img src="http://img141.imageshack.us/img141/6462/discvr5.gif">

From the above diagram and with my extremely shifty logic, I see it as the magnet's north being repelled by the induced North pole in the disc, while the induced south pole is attracted by the magnet's north pole, and thus the disc rotates clockwise - obviously wrong.

So... how does this diagram really work?

 

[twilight1412]

i like to think of it like this
say the magnet is moving up
then relavtive to the magnet the disc must be moving down
by lenz's law it must induce a current to induce a force to oppose the motion which caused it
the current being eddy currents and
the motion being the downward motion and therefore results in an upward motion