This demonstration exhibits forces on current carrying wires when placed inside a magnetic field. The magnetic field can come in fact, from another current carrying wire. This is the principle of the first demonstration. A direct current is passed through the two wires in opposing directions, causing the wires to stick together.

In the second variant of this demo, permanent magnets are placed below a coil of wire. When the current is switched on, the coil experiences a force that is perpendicular to the magnetic field. The force moves the coil either in the backward or forward direction depending upon the polarity of the magnets. If the polarity switches periodically, the coil could be rotated like a pendulum.