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ArrowHeinrich Friedrich Emil Lenz (1804-1865)

Heinrich Friedrich Emil Lenz

At the turn of the 19th century, scientists were beginning to gain a rudimentary understanding of electricity and magnetism, but they knew almost nothing about the relationship between the two. Baltic German physicist Heinrich Lenz took the first step toward filling this gap with his formulation of Lenz’s law, his most enduring contribution to physics.

Lenz’s Law states that the introduction of a conductor within an electromagnetic field will produce electricity, inducing an opposing magnetic field that repels the magnetic field producing the charge.

In short, Lenz’s law is a consequence of the conservation of energy. According to the law, the total amount of energy in the universe must remain constant. If the magnetic field associated with the current moves in the same direction as the change in magnetic field that created it, these two magnetic fields would combine to create a net magnetic field that would induce a current with twice the magnitude.

At approximately the same time Lenz was conducting his research in this area, scientists Michael Faraday of England and Joseph Henry of America were making similar discoveries. Some in the scientific community suggested that Lenz was the shrewdest of the three, but not the most brilliant. Both Faraday and Henry, while rising stars in this new field, failed to properly quantify or extrapolate their findings; Lenz however, showing scientific acumen unusual for the time, carefully documented all phases of his research, making it easier for future scientists to cite his work.

Besides the law named in his honor, Lenz shares billing with James Prescott Joule on the Joule-Lenz law, with both making similar, independent discoveries at about the same time. The law provides a quantitative analysis of the speed at which resistance in a circuit changes electric energy into heat energy.

Lenz’s name, or at least his first initial, is attached to still one more area of physics nomenclature. The symbol “L” was chosen to represent “inductance” in honor of his pioneering work in electromagnetism.

After suffering a stroke, Lenz died in 1865 while in Rome. Beyond his breakthrough discoveries, he is fondly remembered in the scientific community for thoroughly testing every aspect of his findings and accounting for every possible variable that might arise in the course of research.


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