Jefferson Lab's Workbench Projects
The Electromagnet Experiment Stand consists of a coil wound from approximately 49 meters (160 feet) of 22 gauge solid core, enamel insulated magnet wire. The electromagnet's core consists of a 5/8" diameter, 5 3/8" long hex bolt. The coil was wrapped around the core in six layers, each containing approximately 130 turns, for a total of roughly 780 turns. The coil is tapped between the 3rd and 4th layers so that the inner three layers of the coil can be powered independently from the outer three layers. The electromagnet is powered from a 5 volt, 2.2 amp power supply. As the full coil has a resistance of about 2.6 ohms, nominal current draw is about two amps. A 1.3 ohm load is added to the circuit when the inner three layers of the coil are not used in order to keep the current flowing through the coil constant. An additional 2.5 ohm load can be added to the circuit in order to reduce the current flowing through the coil by roughly half. The different settings are controlled by a pair of toggle switches mounted to the front of device, one to control the amount of current flowing through the coils and one to control the number of active coils.
The main base is constructed from sections of 1 × 4 white pine and 1/4" plywood. The electromagnet is suspended above the main base with a support frame made from sections of 1 × 2 white pine.