Search
286 items
Faraday Disk
Invented by Michael Faraday in 1831, his Faraday disk showed the connection between electricity and magnetism by producing an electric current between the center of the disk and its rim as the disk is rotated by a hand crank.
The disk center and rim are connected to the terminals, the rim via a mercury bath on the base. The copper rim passes through the bath.
This Faraday disk is a demonstration motor. With a battery or DC power supply connected to the terminals, the disk rotates due to the force on the moving charges produced by the magnetic field from the horseshoe magnet.
We no longer use this demonstration to avoid possible mercury vapor emission due to electrical sparks at the copper-mercury connection.
Galvanometer Ayrton Shunt
Universal Ayrton Leeds & Northrup shunt for any galvanometer. . Decreases galvanometer sensitivity by shunting a selected fraction of the input current to bypass the galvanometer. Shunt resistance affects galvanometer damping.
Date Unknown.
Model No. 2116, Serial No. 275073
Induction Coil
Induction coil probably manufactured or at least marketed by Cental Scientific Company. The coil matches the image of another coil with a Central Scientific nameplate. The nameplate is missing from our coil, but the mounting spots are visible. Nameplates containing Central Scientific Company were probably manufactured between 1900 and 1909 with those containing the trademark CENCO manufactured after 1909.
Signal Corps Test Unit I-176
Signal Corp Test Unit I-176, serial no. 0238, containing a Triplet Elec. Inst. Co. multimeter. The Physics Department probably obtained this unit from army surplus in the decades following World War II.
L. Bradley Circular Resistance Box
Circular resistance box manufactured by L. Bradley & Co. in Chicago. Patent date is Jan. 7, 1873. Construction of box consistent with 1870s technology. Box was probably used in trouble shooting telegraph or possibly telephone lines. We have no further information about the box.