Tangent galvanometer by Elliott Bros.

Made:
1864-1886
maker:
Elliott Brothers
Tangent galvanometer by Elliott Bros

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Tangent galvanometer by Elliott Bros
Science Museum Group
© The Board of Trustees of the Science Museum

Tangent galvanometer by Elliott Bros., Helmholtz type with pivoted needle. Helmholtz refined the tangent galvanometer (first described 1837) in 1849, adding a second outer coil in order to make the magnetic field between the coils, where the galvanometer needle sits, essentially uniform. When at rest, the galvanometer needle and coils are parallel to each other and to the Earth's magnetic field. When current flows, the needle deflects, and the amount of current flowing is exactly proportional to the trigonometric tangent of the angle through which the needle has turned.

Details

Category:
Electricity and Magnetism
Object Number:
1974-578
type:
galvanometers