Editing Hermann von Helmholtz (section)

===Electromagnetism===

Helmholtz studied electrical oscillations from 1869 to 1871, and in a lecture delivered to the Naturhistorisch-medizinischen Verein zu Heidelberg (Natural History and Medical Association of Heidelberg) on 30 April 1869, titled ''On Electrical Oscillations'', he indicated that the perceptible damped electrical oscillations in a coil connected to a [[Leyden jar]] were about {{frac|1|50}} second in duration.<ref>{{cite book|url=https://books.google.com/books?id=JCNWAAAAMAAJ&q=electrical+oscillation+helmholtz&pg=PA268|title=Hermann von Helmholtz|first=Leo|last=Koenigsberger|date=28 March 2018|publisher=Clarendon press|isbn=978-0-486-21517-4|access-date=28 March 2018|via=Google Books}}</ref>

In 1871, Helmholtz moved from Heidelberg to Berlin to become a professor of physics. He became interested in [[electromagnetism]], and the [[Helmholtz equation]] is named for him. Although he made no major contributions to this field, his student [[Heinrich Rudolf Hertz]] became famous as the first to demonstrate [[electromagnetic radiation]]. [[Oliver Heaviside]] criticised Helmholtz's electromagnetic theory because it allowed the existence of [[longitudinal wave]]s. Based on work on [[Maxwell's equations]], Heaviside pronounced that longitudinal waves could not exist in a vacuum or a homogeneous medium. Heaviside did not note, however, that longitudinal electromagnetic waves can exist at a boundary or in an enclosed space.<ref>John D. Jackson, Classical Electrodynamics, {{ISBN|0-471-30932-X}}.</ref>