While building electromagnets, Henry discovered the electromagnetic phenomenon of self-inductance. He also discovered mutual inductance independently of Michael Faraday, though Faraday was the first to make the discovery and publish his results. Henry developed the electromagnet into a practical device. He invented a precursor to the electric doorbell (specifically a bell that could be rung at a distance via an electric wire, 1831) and electric relay (1835). His work on the electromagnetic relay was the basis of the practical electrical telegraph, invented separately by Samuel F. B. Morse and Sir Charles Wheatstone. In his honor, the SI unit of inductance is named the henry (plural: henries; symbol: H).
Key Facts
- Born: December 17, 1797 in Albany, New York, U.S.
- Died: 1878
- Field: Science
Legacy and Impact
The influence of Joseph Henry extends far beyond his own lifetime. He fundamentally shaped our understanding of the natural world, and his discoveries and theories remain foundational to this day.
Though he passed away in 1878, his ideas continue to be studied, debated, and built upon by scholars and practitioners worldwide.
Joseph Henry remains one of the most celebrated minds to emerge from United States, a testament to the rich intellectual heritage of the region.
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