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1800
William Herschel, a British astronomer, discovered infra-red radiation (heat waves). -
1801
German chemist Johann Ritter discovered UV radiation. -
1885
James Maxwell, a British scientist, predicted the existence of continuous EM waves. -
1887
German scientist Heinrich Hertz discovered radio waves. -
1895
German physicist Wihelm Roentgen discovered x-rays. -
1896
French physicist Henri Becquerel discovered radioactive rays emitted by uranium. -
1898
Marie Curie discovered radium. -
1900
Frenchman Paul Villard discovered gamma rays.