1820 "Experimenta circa effectum conflictus electrici in acum magneticum". Hans Christian Oersted

Danish physicist Hans Christian Ørsted accidentally discovered that the change in electric field creates magnetic field
One week after Ørsted's discovery, French physicist André-Marie Ampère published his law. He also proposed right hand screw rule

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21 June 1820 Death of Alexis Thérèse Petit

20 August 1820, Death of Andrew Ellicott in West Point, New York, USA

1820 Birth of John Tyndall

1820 Birth of Jean-Charles-Hippolyte-Joseph Houzeau de Lehaie

Chronology 1819 - 1820 - 1821