What is a physical discovery you made

The discovery of radioactivity

Many discoveries in science have already been made by chance. So it was with the discovery of radioactivity. She was from Antoine Henri Becquerel(1852-1908) who dealt with the question on February 26, 1896:

Can sunlight make crystals shine?


Becquerel came up with a simple method to detect such rays: He placed various crystals between photographic plates, which were enclosed light-tight in dark paper. He placed a wire mesh made of copper between the photo plates.

If sunlight could stimulate the crystals to emit something like X-rays, then those rays should penetrate the dark paper, but the copper wires should create a shadow image on the exposed and developed image.

(Source: http://www.chemie.uni-bremen.de/stohrer/biograph/becqah.htm)

Chance brought the discovery:

Becquerel also examined uranium salt, namely uranium-potassium-hydrogen sulfate, as a crystal sample.

But in the days of the experiment the weather was pretty bad and so he stopped all attempts, but left them standing. He put only the unwrapped plates in a showcase drawer, the uranium salt stayed in its place. There was no sun on the following days. A few days later he developed the already exposed plates for routine control. He expected only faint images, but instead found a clear shadow on the images (see picture). For 2 months he kept the salts sealed in a lead cassette, which was kept in the dark.

Even under these conditions, the salts continued to emit rays.

> (Source: Physics Book / Intermediate Level, Dorn Bader)

All of the uranium salts examined by him led to the same result, regardless of whether they were phosphorescent, were in solution or were shielded from light.

Becquerel attributed this radiation to the element uranium, and he was right. Thus the first radioactive element was discovered

It turned out that other elements also emit such rays.

Becquerel's student, Marie Sklodowska Curie (1867-1934), observed in 1898 that similar rays are emitted by the element thorium. When she discovered that the radiation from pitchblende - an ore containing uranium - was more intense than that of uranium, she concluded that the ore must contain more unknown radioactive elements. Finally, in 1898, she first isolated the polonium from the pitchblende and later, together with her husband, Pierre Curie (1859-1906, French physicist), the highly radioactive element radium.

In 1903 Marie Curie received the Nobel Prize in Physics together with her husband Pierre Curie and Antoine Henri Becquerel. This made her the first woman ever to receive a Nobel Prize.

Marie and Pierre Curie in their bad

equipped test laboratory.

(Source: http://www.chemie.uni-bremen.de/stohrer/biograph/curie.htm)

Stefan Kissling, Constantin Ludmann, 10c