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The National MagLab is funded by the National Science Foundation and the State of Florida.

Galvanometer - 1820

A galvanometer is an instrument that can detect and measure small amounts of current in an electrical circuit. 

Mirror Galvanometer thumbnail

The first galvanometer was built just months after Hans Christian Ørsted demonstrated in 1820 that an electric current can deflect a magnetized needle.

The device was assembled by German mathematician and physicist Johann Schweigger, who called it a multiplier.

A galvanometer consists of a needle attached to a coil mounted so that the coil is allowed to pivot freely within a magnetic field created by the poles of one or more permanent magnets.

When electricity is allowed to pass through the coil, the magnetic field generated by the current-carrying wire interacts with the field of the permanent magnets, generating a twisting force known as torque that rotates the coil. The deflection of the galvanometer’s needle is proportional to the current flowing through the coil.