On the 29th August 1831 Michael Faraday achieved one of his greatest successes, discovering how to make electricity from magnetism.
Faraday’s first ‘Electromagnetic Induction Ring' is made from 2 sections of wire insulated with cotton and then coiled around opposite sides of an iron ring. When Faraday passed an electric current through one coil he induced an electric current in the other coil, which flowed for a very brief period of time and caused the needle on a galvanometer to move.
He wrote in his scientific notebook:
Aug 29th 1831
1. Expts on the production of Electricity from Magnetism, etc. etc.
2. Have had an iron ring made (soft iron), iron round and 7/8 inches thick and ring 6 inches in external diameter. Wound many coils of copper wire round one half, the coils being separated by twine and calico – there were 3 lengths of wire each about 24 feet long and they could be connected as one length or used as separate lengths. By trial with a trough each was insulated from the other. Will call this side of the ring A. On the other side but separated by an interval was wound wire in two pieces together amounting to about 60 feet in length, the direction being as with the former coils; this side call B.
3. Charged a battery of 10 pr. plates 4 inches square. Made the coil on B side one coil and connected its extremities by a copper wire passing to a distance and just over a magnetic needle (3 feet from iron ring). Then connected the ends of one of the pieces on A side with battery; immediately a sensible effect on needle. It oscillated and settled at last in original position. On breaking connection of A side with Battery again a disturbance of the needle.
4. Made all the wires on A side one coil and sent current from battery through the whole. Effect on needle much stronger than before.
5. The effect on the needle then but a very small part of that which the wire communicating directly with the battery could produce.
From this experiment Faraday would go on to develop the first ever generator a few months later.
Faraday’s Ring and scientific notebook can be found within the museum and archival collections of the Ri.