1896 Birth of Nuclear Physics ~ discovery of radioactivity

Nuclear Physics was born in 1896, when the French scientist Henri Becquerel discovered [radioactivity] almost by accident.

Henri Becquerel (1852 - 1908) Becquerel placed a photographic plate wrapped in black paper and some uranium salt in a drawer. A few days later, he found that the photographic plate had been blackened. Some invisible radiation had penetrated through the paper and blackened the plate. Becquerel identified the uranium as the source of the radiation by testing various uranium compounds and some powdered uranium. This phenomenon is called radioactivity and the substances that emit radiation are said to be radioactive.

Becquerel's Experiment

Instructions : Place a sealed radioactive source, such as strontium, above a dental X-ray film wrapped in plastic bag. (Right: Apparatus used in Becquerel's Experiment)

Results:

• The photographic film has been blackened by radioactivity except in the shadow of the key.

This discovery of radioactivity triggered off a number of investigations of the phenomenon. Later, more and more scientists entered the field of nuclear physics and many new discoveries followed.

*back to* [discovery] [experiment]                           (C)1999 ThinkQuest Team 27954