Damping by Eddy Current Losses

Dual Electromagnet Apparatus connected to a DC switch

Concept Overview:

1. Eddy currents can create a damping of mechanical motion.

Lecturer Procedure

Step(s) to Follow	Expected Result
1. Hang the solid disc from the hooks on the apparatus. 2. Pull the disc to approximately a 45 degree angle. 3. Release disc. 4. Allow a few swings to pass. 5. Turn on the DC switch at the peak of its path.	Disc will stop between the two coils.
1. Switch out the solid disc for the slotted disc and repeat the previous steps	The disc's motion will not be deterred this time.

Step(s) to Follow

Expected Result

1. Hang the solid disc from the hooks on the apparatus.

2. Pull the disc to approximately a 45 degree angle.

3. Release disc.

4. Allow a few swings to pass.

5. Turn on the DC switch at the peak of its path.

Disc will stop between the two coils.

1. Switch out the solid disc for the slotted disc and repeat the previous steps

The disc's motion will not be deterred this time.

Variation: After lecture, invite students to come down and try to push the disc back and forth between the poles of the electromagnet - it will feel as though it's moving through a viscous liquid.