Faraday's Law Demo: Pipe and Magnet

This is a demonstration of eddy currents resulting from Faraday's law. While a steel ball dropped into a vertical aluminum pipe falls with the acceleration of gravity, a magnet sphere takes many seconds to make the journey through the pipe. The reason is that the movement of the magnet changes the magnetic flux through the tube, which generates eddy currents through Faraday's law, which create induced magnetic fields that oppose the original direction of the field of the magnet and slow the progress of the magnet through the tube. This demonstration was created at Utah State University by Professor Boyd F. Edwards, assisted by James Coburn (demonstration specialist), David Evans (videography), and Rebecca Whitney (closed captions), with support from Jan Sojka, Physics Department Head, and Robert Wagner, Executive Vice Provost and Dean of Academic and Instructional Services.