This demonstration shows the production of eddy currents in a nonmagnetic conductor (aluminum) when passed through a magnetic field. 

When setup of the pendulum is like image 1 then the motion of the pendulum through the magnet produces currents flowing in the metal. This in turn produces a force in opposition to the direction of the pendulum motion which then causes the movement of the pendulum is quickly damped out.  With the pendulum reversed, the slits in the portion of the pendulum which swings through the magnet prevents the formation of significant eddy currents, and the pendulum continues to swing.

An acrylic pendulum with a coil of fine wire attached to it can be substituted for the aluminum pendulum.  As the coil swings through the magnetic field, generated currents can be measured with a galvanometer.