An electromagnet with an extended core is mounted on a wooden base. Put the coil of wire with a small light bulb connected across it around the core. When the oscillating magnetic field is activated, the bulb lights. There is also a two-coil light-bulb system. One can put the coils in different orientations so that the bulb either gets brighter or dimmer. Please do not turn the variac over 90 volts. (Uses some of the same equipment as the jumping ring demo.)