Curie Point De-magnetizer

Creates non-magnetic iron.

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Purpose -

This shows the de-magnetizing effect of heat on metals.

Nature - 

Demonstration

Materials - 

three stands, 10cm of steel wire, a small magnet, string, a power pack, two leads with alligator clips.

Method - 

· Between two of the stands, reasonably low, attach the piece of steel wire.

· Attach the magnet to the string and hang it as a pendulum from the third stand.

· Arrange the pendulum so that the magnet is stuck to the steel wire and  held out from a vertical drop.

· Attach the leads to each end of the wire and then to the power pack.  Set the power pack to six volts then turn it on.  The wire will heat up and glow.  At some point the magnet will no longer hold and swing away from the wire.

· Turn off the power.  The magnet is now able to reattach.

Safety -

Be careful of the extremely hot wire.

Explanation -

The atoms of iron and nickel are each magnetically charged, however in normal samples these are arranged randomly.  When they are all aligned the piece is a magnet.  When a magnet is placed against some non-magnetic iron, the atoms temporarily line up allowing it to hold to a magnet.  If this metal is heated however, the atoms move so violently that they are unable to line up properly and are no longer able to hold a magnet.

Notes -

If it does not work on six volts simply switch to a higher voltage.

The temperature at which a metal is no longer able the hold a magnet is called it's Curie point, named after its discoverer Pierre Curie.

This is part of the mechanism that drives a modern circuit breaker.