Heinrich Lenz

Emile Heinrich Friedrich Kristianovich Lenz (February 24, 1804-February 10, 1865) was a Russian physicist and geophysicist.

Lenz was born in 1804 in the occupied city of Delpat, Estonia (now Tardu in the Republic of Estonia). At the age of 16, he was admitted to Delpat University with excellent grades. In 1828, Lenz was elected as a junior scientific assistant of the St. Petersburg Academy of Sciences in Russia. In 1830, he was elected as a correspondent member of the St. Petersburg Academy of Sciences. In 1834, he became an academician. From 1836 to 1865, he was a professor at St. Petersburg University. In 1840, he served as the head of the Department of Mathematical Physics at St. Petersburg University. In 1863, he was elected as the first rector. Lenz died of a stroke in Rome, Italy in 1865.

Lenz summarized Ampere's electrodynamics and Faraday's electromagnetic induction phenomenon. In 1833, he read a paper entitled "On Determining the Direction of Induced Current by Electromechanical Method" at the St. Petersburg Academy of Sciences, proposing that the induced electromotive force prevents the movement of magnets or coils that generate electromagnetic induction. Later, this law was called Lenz's law and published in the Annals of Physics and Chemistry in 1834. Then German physicist Helmholtz proved that Lenz's law is actually the law of conservation of energy for electromagnetic phenomena.

In 1842, Lenz determined the relationship between current and the heat it produced independently of the British physicist Joule, which is Joule's law. Therefore, Joule's law is also called Joule-Lenz's law. Lenz also studied the resistivity of different metals and the relationship between resistivity and temperature. In addition, with the initiative and assistance of Lenz, the Russian Geographical Society was established in 1845.