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 7 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 5 years ago

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


Viewed
45004 times

More from MIT Department of Physics Technical Services Group

MIT Physics Demo -- Back "emf" in a Large Solenoid

MIT Physics Demo -- Back "emf" in a...

Added 8 years ago | 00:00:23 | 67310 views

MIT Physics Demo -- Dipole Antenna

MIT Physics Demo -- Dipole Antenna

Added almost 8 years ago | 00:00:57 | 42708 views

Ripple Tank: Single and Double Slit Diffraction and Interference

Ripple Tank: Single and Double Slit...

Added almost 7 years ago | 00:03:05 | 60503 views

MIT Physics Demo -- Microwave Polarization

MIT Physics Demo -- Microwave Polar...

Added almost 8 years ago | 00:01:14 | 36934 views

MIT Physics Demo -- Exploding Wire

MIT Physics Demo -- Exploding Wire

Added almost 8 years ago | 00:02:00 | 61800 views

Two Dimensional Collisions

Two Dimensional Collisions

Added almost 7 years ago | 00:01:19 | 47279 views