Permanent Magnet Switch

This magnetic experiment shows how to create an on/off switch with permanent magnets.

Step 1: What You Need

Here are the supplies you need for replicating this experiment:

- 4 pieces of iron

- 2 magnets, one stronger than the other (or three same size magnets two between the top plates and one between the bottom plate)

- Two interlocking wood or other non-ferromagnetic pieces

- couple of stainless steel nuts and bolts (not attracted by magnets)

Start by cutting the metal pieces, the ones I used were 5mm in thickness, smaller pieces: 40mm x 50 mm, bigger pieces: 90 x 50 mm. The dimensions are not important. The size of the magnets determines what the dimensions of the iron plates should be - all of the magnet's north and south pole side should be in touch with the iron. If you have only one size magnets. You can use two magnets between the top plates and one between the bottom plates. The point is there should be more magnetism between the top plates than between the bottom plates.

Drill holes to the iron plates and to the wooden parts and secure them with the non-ferromagnetic fasteners (stainless steel)

The interlocking wood parts just make the function of this apparatus more user friendly. Keep in mind that it is crucial that the bottom and top plates are in contact when in attraction and no-attraction mode.

Step 2: The Function

No-attraction mode: there is still a tiny amount of magnetism left in the lowest part of the metal plates and the magnetism gradually increases moving upwards the top plates. The magnetic field somehow collapses between the magnets and the top magnet is stronger in the no-attraction mode. I'm struggling to understand the magnetic field behavior in this no-attraction mode - if anyone can help me understand it I would greatly appreciate it

Attraction mode: there is more magnetic attraction between the top plates than bottom plates because the magnet is stronger between the top plates.