Sunday, February 25, 2018

THIS WEEK IN SCIENCE HISTORY: Radioactivity

After the discovery of X rays at the end of 1895, Henri Becquerel began to investigate if there was a connection between invisible radiation and visible light. To test this connection, he placed phosphorescent crystals upon a photographic plate that was wrapped in opaque paper (only a penetrating radiation could reach the emulsion). He then placed this in sunlight for several hours, which excited the crystals in the customary way. Upon development, the photographic plate showed silhouettes of the mineral samples. On February 24, 1896 Becquerel reported his discovery to the Académie des Sciences. He noted that specific salts of uranium were particularly active. This phenomenon was later named by Marie Curie as radioactivity.

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