Magnetism and Electromagnetism
Development of the Electromagnet
In 1819, Hans Oersted (1777-1851) found that an electrical current, when passed through a straight piece of wire, deflected the needle on a compass. He published his findings in a small pamphlet in 1820, probably one of the last great scientific discoveries to be published entirely in Latin.
His discovery showed there was a connection between electricity and magnetism and prompted a whirlwind of further investigation by others. In 1825 William Sturgeon developed the first practical electromagnet by loosely winding a coil of un-insulated wire around a horseshoe-shaped piece of iron. To prevent the wire from shorting Sturgeon coated the iron in varnish. The seven-ounce magnet was able to support nine pounds of iron using the current from a single cell.
In 1830, Joseph Henry dramatically improved on Sturgeon's electromagnet by using cotton insulated wire (probably the first time this was done) and winding hundreds of turns around an iron core. With other modifications, Henry constructed 21-pound "experimental magnet" able to support 750 pounds.
Magnetic/Electromagnetic Apparatus from the collection: