What you'll need:
- A strong magnet
- A section of copper pipe
- A section of some other material pipe (or even a toilet paper/paper towel roll)
- Stand thepipes up on end, or your student can hold them in their hand, vertical.
- hold the magnet over the opening on one end of the non-copper tubing
- let the magnet drop, it will fall right down at the forces of gravity
- now hold the magnet over the opening at one end of the copper tubing
- let the magnet go, watch what happens!
The magnet will float in the copper tube. This is the result of a specific form of Electro-Magnetic force called the Eddy current. As you know, copper is a conductor of electricity. When the magnetic field interacts with the surface of the tube, the metal begins to generate its own magnetic field/current. This was discovered by a scientist by the name of Michael Faraday. The magnetic field created in the metal opposes the one surrounding the magnet. What happens when the same polarized ends of 2 magnets interact? They push eachother away. The same is true here. The magnetic field generated in the pipe is calle the Eddy Current. This all falls within the Physics law called Lenz's Law. Older kids can research Michael Faraday and the Russian physicist Heinrich Lenz. For another simple experiment demonstrating Lenz's Law, check out the Swinging Magnet experiment http://www.ndt-ed.org/TeachingResources/NDT_Tips/LenzLaw.htm