Jumping Ring

electromagnetic induction - temperature coefficient of resistance - magnetic levitation

What it shows:
The induced current in a metal ring is dramatically increased by lowering the ring's temperature.

How it works:
Here is an extension of the Ring Flinging demo. By placing the aluminum ring in liquid nitrogen, you can decrease its resistance by a factor of about 2. Pull the ring out of the LN₂, place it on the solenoid and hit the on switch, and send the ring to the roof.

Setting it up:
Along with the ring flinger, have a dewar^tot with LN₂ and a pair of tongs to fish the ring out. The lecturer should be equipped with a safety helmet; this not only adds to the anticipation, it could also prove useful!

Comments:
See details of the Ring Flinger. Rating ***

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