Joseph Henry

Picture of Joseph Henry

Date of Birth: 12/17/1797

Age: 80

Place of Birth: Albany

Citizenship: United States


Read accidentally fell into his hands a book on physics interested in this science, and was able to enter the Academy in Albany. At the same time he worked as a school teacher, then assistant professor of chemistry, experiments demonstrated during public lectures. Upon completion of the Academy (1822) he worked as an inspector on the Erie Canal, and then got a job as a teacher of mathematics and physics in Albany. By making the summer one of the classes to the lab, he began to experiment on electromagnetism and in 1828 constructed a powerful horseshoe magnet with a multi-layer coil, able to lift a weight of a ton. The experiments with electromagnets led him to the idea of ??producing electricity via a magnetic field, and later, in 1831, to the discovery of the phenomenon of electromagnetic induction. Henry did not suspect that a similar experiment was engaged at the time M.Faradey English physicist, who in February 1832 published the results of research "on the volt-electric and magneto-electric induction" in the "Proceedings of the Royal Society." The first article about this same Henry opening appeared in print only in July of the same year. At the time of visit Henry in Albany are two more of his important scientific achievements: the discovery of the self-induction phenomenon (he watched it in 1831, but an article about it published only in 1838) and the invention of the electric switch and the electromagnetic telegraph (in this he was ahead of Morse 6 years) . The telegraph worked in the territory of Princeton College and transmit signals over a distance of one mile.

In 1832, Henry became a professor at Princeton College (now Princeton University) in 1846 - the director of the Smithsonian Institution in Washington. These years of his research include the relationship of the induced currents. He studied the relationship of mutual induction on the distance between the coils, has shown that a suitable choice of the number of turns in the windings can raise or lower the voltage (in this printsipurabotayut current transformers). His latest work in the field of electricity Henry Hertz ahead: in 1842 he discovered that the iron bars that are in the basement of the building, are magnetized by an electric spark produced on the second floor. 25 years later, Maxwell described all that he had discovered Henry, with the four equations of electrodynamics.

Henry was one of the top 50 outstanding scientists included President Lincoln of the US National Academy of Sciences (1863), and from 1868 until his death was its permanent president. In the name of the scientist called the unit of measurement of inductance. Henry died in Washington, DC May 13, 1878.