Demos: 6D-08 Magnetic Braking
An aluminum disk is suspended in such a way that it can oscillate between the poles of an electromagnet. When the magnet is turned on the oscillations are heavily damped because of the eddy currents set up in the disk.
Directions: With the magnet turned off, pull the disk back and let it go. It will swing like a pendulum with very little damping. The turn the magnet on and repeat. This time the disk comes to rest almost immediately upon entering the field.
Suggestions for Presentation: Begin the discussion by referring to the Demo 6D - 07. Based on those results, ask the students to predict what will happen when the disk swings down through the B-field. Ask for suggestions as to how this might be used.
Applications: Magnetic Braking