SUBJECT: The Falling Coil Applet
NOTE: You must be connected to the Internet to view this simulation!
DESCRIPTION: This applet shows the dynamics of a conducting non-magnetic ring falling on the axis of a fixed magnet. As the ring falls under gravity towards the magnet, the changing magnetic flux through the ring gives rise to a current which is in a direction such as to slow the fall of the ring, by Lenz's Law. The ring has mass m, resistance R, and self-inductance L, and the magnet has magnetic dipole moment M. You can vary the resistance of the ring and the strength of the magnetic dipole moment to see how these parameters affect the dynamics of the ring. If the resistance is zero and the dipole moment is strong enough, the ring will levitate above the magnet. If the resistance is non-zero, even though small, the ring will eventually fall past the magnet. We also show the induced current in the ring in the meter on the lower left.
VISUALIZATION: Start Simulation (you must have Java™ J2SE v1.4+ JRE installed. Mac OS X users need the Java3D update.)