Magnet dropping through a loop

[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 \muz. 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?

 

[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.