# Magnet dropping through a loop

1. Apr 16, 2010

### semc

A permanent magnet of mass m is located on the vertical axis of a stationary, conducting , non-magnetic ring for a long time. The ring has a radius a, resistance R and inductance L.At time t=0 the magnet is released. Suppose the magnet has dipole moment $$\mu$$z. Write down the equation of motion.

Is the retarding force due magnetic flux generated by the induced current passing through the loop? If that is the case how do I evaluate the equation of motion of the magnet?

2. Apr 16, 2010

### chrisk

Consider Lenz' Law. Energy must be conserved, so the work done to create the current in the loop must equal the thermal energy generated in the loop.

Last edited: Apr 16, 2010