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Demo Kit - CNA Videos

The CAP has prepared a kit which is meant as an instructional tool and as a provocation. High school physics teachers can use this kit as a demonstration of some very basic electromagnetic physics. It can be easily and cheaply reproduced. The kit contains three sheets of various materials, a penny and a very strong magnet. The demonstration generally consists of three steps:

1. Incline the sheet of plexiglass at an angle and allow the penny and the magnet to run a race, sliding on their sides (not rolling) down the sheet. This should be pretty much a dead heat and pretty boring.

2. Incline the sheet of steel at a similar angle and run the same race, which is now even more boring, as the magnet will just stick to the steel, while the penny slides down.

3. Incline the sheet of aluminum at the same angle and run the race again. The kinetic energy lost by the magnet, due to the induction of eddy-currents in the aluminum, will mean that it arrives at the bottom significantly later than the penny.

NOTE:     If you want to demonstrate, cleverly, that pennies are not magnetic, and not attracted by the magnet, be sure NOT to use Canadian pennies from 2003-2004, as these contain enough magnetic material to be STRONGLY attracted to the magnet! (2003 Canadian pennies are made of steel coated with copper. Examining 2 new-looking 2004 pennies, one observer noted that one was magnetic, and the other not. On closer inspection, the magnetic pennies all had (p)'s under the Queen's head. Before 1982, US pennies were made of 95% copper and 5% zinc. This got too costly, so they now contain 97.6% zinc and just a very thin layer of copper.)

THERE ARE A LIMITED NUMBER OF KITS AVAILABLE FOR PURCHASE at a cost of $15.00 (taxes included) -- limit of one per school. They will be distributed on a first-come, first-served basis. Click here to order a kit.

Alternatively, you can request a visit from a local university physics graduate student or professor who can bring the demonstration to your school. Please complete the request form and the CAP will do its best to find an available representative to come to your school.