SUBJECT: The Floating Coil Applet
NOTE: You must be connected to the Internet to view this simulation!
DESCRIPTION: This applet illustrates the forces on a current carrying coil sitting on the axis of a permanent magnet. For current flowing in one direction in the coil the force on the coil will be upward, and if the current is strong enough the coil will levitate, floating on the magnetic fields of the coil plus the magnet. This is the way one form of MagLev works. For the other direction of current the coil is attracted to the magnet The magnet has its north pole at the top, and the direction of positive current is counterclockwise when viewed from above. The coil initially rests at one coil radius above the magnet on a platform. There is a marker at two coil radii above the magnet. This quantitative problem (PDF) gives you an idea of the currents you need to get levitation in the simple experiments which this applet illustrates.