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Horseshoe-shaped electromagnet

Scientific Instruments & Research

Ophthalmic electromagnet, United Kingdom, c. 1940

Ophthalmology

1935-1945

Electromagnet used by James Jo

Scientific Instruments & Research

Cased electromagnet

Telecommunications

Electromagnet used by James Joule in about 1839 for experiments on the attracting power of magnets. Iron bar is wound with '88 yards of covered copper wire 1/16" diameter.' One of a pair of magnets used to test the law that 'the attractive force of two electromagnets is directly proportional to the square of the electric force to which the iron is exposed', i.e. M (attraction) = E squared (electric current) x W squared (length of wire). Results showed that as the length of the bar is increased, so the power of attraction increases.

Electromagnet used by James Jo

Scientific Instruments & Research

Electromagnet used by James Joule, c.1855.

Part of Electromagnet

Scientific Instruments & Research

1855

Electromagnet used by James Joule, c.1860.

Part of Electromagnet

Scientific Instruments & Research

1860

Electromagnet core used by James Joule, c.1860. Cylinder of concentric layers of soft iron insulated by cotton tape.

Electromagnet Core

Scientific Instruments & Research

1855-1865

Replica of an electromagnet used by James Joule, the original of which was used in 1843 to demonstrate the heating effect of an electric current. Horizontal glass cylinder wound with cotton fabric. Armature of metal strip bound together and wound with cotton-covered copper wire.

Replica of James Joule's Electromagnet

Scientific Instruments & Research

Electromagnet core made by James Joule for electromagnetic engine. Used to experiment on the shape of wire most suited to Joule's electromagnetic engine. The practical advantage of the solid magnet outweighed the wire magnet. Described in Joule's 1839 paper 'On the use of Electro-magnets made of iron Wire for the Electromagnetic Engine'

Electromagnet core

Scientific Instruments & Research

1835-1845

Electromagnet core used by James Joule, c.1860. Made of concentric layers of soft iron insulated by cotton tape.

Electromagnet Core

Scientific Instruments & Research

1855-1865

Electromagnet made by James Joule for experiments on lifting power, c. 1840. One of a number of electromagnets constructed to investigate how much work could be extracted, Experiments carried out at Salford brewery. Long cylindrical piece of iron divided in two longitudinally; one half wound with cotton-covered copper wire, other half wound only in centre. Both halves have eyelet drews along their length.

Electromagnet

Scientific Instruments & Research

1840

Ferranti,electromagnet

Electricity and Magnetism

Electromagnet used by James Joule, c.1855.

Part of Electromagnet

Scientific Instruments & Research

1855

Electromagnet type E serial no. 7156/6 by Newport Instruments, Newport Pagnell, England

Electromagnet type E serial no. 7156/6 by Newport

Electricity and Magnetism

1960-1979

Part of electromagnet used by James Joule, c.1855.

Part of Electromagnet

Scientific Instruments & Research

1855

Electromagnet core used by James Joule, c. 1839 to measure electromagnetic attraction. Made up of 16 square sections of iron wires and covered in strips of cotton. Deduced that the attractive force of two electromagnets for one another is directly proportional to the square of the electric force to which the iron is exposed; or if E is electric current, w the length of wire and M magnetic attraction, M=E squared x W squared. Originally 'wrapped with 22 yards of covered wire' now missing.

Electromagnet Core

Scientific Instruments & Research

1839