Magnetic Heat Engine help

[fishbulb]

For my 10th grade chemistry science fair report (it doesn't have to be about chemistry), i chose to determine the Curie temperature, or temperature at which a material loses its ability to be magnetized, of different materials using the magnetic heat engine. http://www.scitoys.com/scitoys/scitoys/magnets/magnets.html#curie_effect

 

Sounds easy right? Well, my dad and i made a rare earth magnet be pulled by another magnet so it is in the candle flame. When the pendulum magnet is resting at the bottom of its swing, the bigger magnet pulls it until it is suspended. Then once it heats up from the candle, it falls back and never returns. We had no idea why that happened.

 

Then we touched the two magnets together and then put the bigger one back where it was and the smaller magnet was attracted to it again, like it magnetized it.

 

Finally, my question, once a material is above its curie point, does it need to be magnetized before it can gain back all of its magnetic properties?

 

Any help on magnets would also be helpful.

[insane_alien]

maybe it just takes too long for it to cool down enough and when its at the bottom of the swing, the attractive force is too small to pull it up. try letting it cool after demagnetiztion and then hold it close(but not touching) to the bigger magnet.

 

solution: get a smaller magnet or one with a lower heat capacity.

[5614]

When the pendulum magnet is resting at the bottom of its swing, the bigger magnet pulls it until it is suspended. Then once it heats up from the candle, it falls back and never returns. We had no idea why that happened.

1) It hasn't properly cooled down.

2) The other magnet is not pulling it strongly enough.

(I'm just repeating what insane_alien said)

 

Finally, my question, once a material is above its curie point, does it need to be magnetized before it can gain back all of its magnetic properties?

If it did then the video on that site, shown here:

http://sci-toys.com/scitoys/scitoys/magnets/curie_engine/curie_engine_closeup.gif

would not work.