On the first day of 1896, on the first day of scientific experimentation due to an experiment of scientist Onari Bekarel, what is radioactivity, it was first detected.
They wrap the photographic plate in black paper and then put the phosphorescent salt on it in the dark. Then using the uranium salt, the plate started black. These radiation were called beakaral rays.
It soon became clear that the black of the plate was not connected to phosphorescent because the plate was black when it was kept in the dark. It was also understood that there is some kind of radiation that can cross the paper and blacken the plate. In 1895, Wilhelm Roentgen researched X-ray.
But still Beckerell thought that he would develop these photographic plates. And they found that the photos are still very clean. This showed that uranium left radiation without any external energy. That was, the first information about radioactivity.
Then he told another experiment that the radiation they found were not X-rays. X-rays are neutral and do not bend when placed in a magnetic field. But these rays turned away.
Baker was born in Paris in 1852. To discover radioactivity, he was awarded the Nobel Prize in Physics in 1903 with Mary and Pierre Curie.