Massachusetts Institute of Technology
Sign in

MIT Physics Demo -- Pendulum and Magnet

A solid copper pendulum is mounted between the poles of an electromagnet (solenoid). The pendulum is set into motion, and then the magnets are turned on. The magnets induce eddy currents in the copper which oppose the motion of the pendulum. The pendulum quickly slows to a stop, demonstrating an effect called eddy current braking. Eddy current brakes are widely used in trains and roller coasters.

When a copper pendulum with strips cut into it is swung between the same magnets, it is not slowed nearly as much as the solid pendulum. This is because the cuts in the copper prevent large eddy currents from forming. Only eddy currents smaller than the strips of copper can be formed.

Comments (1)

why does the perforated copper plate slow down less than the solid pendulum?

Posted almost 9 years by Anonymous User

You need to log in, in order to post comments.

Created
April 15, 2008 11:50
Category
Tags
License
Creative Commons Attribution-NonCommercial (What is this?)
Additional Files


Viewed
48908 times

More from MIT Department of Physics Technical Services Group

Breakdown of Air

Breakdown of Air

Added over 7 years ago | 00:02:09 | 37695 views

MIT Physics Demo -- Dipole Antenna

MIT Physics Demo -- Dipole Antenna

Added over 9 years ago | 00:00:57 | 45302 views

MIT Physics Demo -- Magnetic Deflection of a TV Image

MIT Physics Demo -- Magnetic Deflec...

Added 9 years ago | 00:01:35 | 63885 views

Rubber and Glass Rods with Tinsel and Balloon

Rubber and Glass Rods with Tinsel a...

Added over 8 years ago | 00:02:02 | 44820 views

MIT Physics Demo -- Low Friction Atwood Machine

MIT Physics Demo -- Low Friction At...

Added 9 years ago | 00:00:46 | 51762 views

Breaking Glass with Sound

Breaking Glass with Sound

Added over 8 years ago | 00:02:33 | 69141 views