Damped pendulum: Swinging metal disks damped in magnetic field.

Damped pendulum: Swinging metal disks damped in magnetic field. A strong, stationary magnetic field is created by putting 120 V.D.C across two multi-turn coils with iron cores. A pendulum consisting of a disk at the end of a rod is allowed to swing through the magnetic field. If the disk is solid metal, eddy currents are created in the surface of the disk. The eddy currents create magnetic fields that drag against the field of the electromagnet, quickly slowing the disk. If a slotted disk (slots not reaching the rim) is used, eddy currents form in the bars, and the disk slows quickly. If the slots are open at one end, each bar is an open circuit, and the disk swings freely. Various different Disks can be inserted: 1. solid aluminum 2. partly slotted alum. 3. Alum. slotted to edge 4. copper 5. plastic 6. various others...