Hi, I am working on an experiment to investigate the effect of electrical conductivity of the metals on the levitating force produced. Basically the concept is this: when a metal plate is placed on top of a solenoid (but not touching), as the a.c. flows in the solenoid the change in magnetic flux induce eddy current in the metal plate. The eddy current will flow in a direction such that it opposes the magnetic field that induces it, so a repulsive force will be produced between the solenoid and metal plate. I thought conductivity of metal would affect it as the higher the conductivity the larger the eddy current induced. The problem here is, does paramagnetism, diamagnetism or ferromagnetism affect the repulsive force between the metal plate and the solenoid? Also, does the shape of the metal plate affect the eddy current produced within it? Can I use a flat, square metal plate to substitute metal ring?