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 over 8 years by Anonymous User

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

MIT Department of Physics Technical Services Group

MIT Department of Physics Technical Services Group

Category: Science | Updated over 6 years ago

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


Viewed
47549 times

More from MIT Department of Physics Technical Services Group

Temperature Effect on Resistance

Temperature Effect on Resistance

Added 8 years ago | 00:01:10 | 47865 views

MIT Physics Demo -- Conducting Glass

MIT Physics Demo -- Conducting Glass

Added over 8 years ago | 00:01:11 | 56246 views

Ripple Tank: Single and Double Slit Diffraction and Interference

Ripple Tank: Single and Double Slit...

Added over 7 years ago | 00:03:05 | 63025 views

Soap Film Oscillation

Soap Film Oscillation

Added over 7 years ago | 00:04:27 | 50164 views

MIT Physics Demo -- Conductivity of Ionized Water

MIT Physics Demo -- Conductivity of...

Added over 8 years ago | 00:00:53 | 50864 views

Hinged Stick and a Falling Ball

Hinged Stick and a Falling Ball

Added over 6 years ago | 00:01:23 | 23066 views