Which German physicist's discovery of X-rays inspired Becquerel's uranium-salt experiments?

The German physicist whose discovery of X-rays inspired Becquerel’s uranium-salt experiments was Wilhelm Röntgen.

Röntgen discovered X-rays in late 1895 while investigating cathode-ray tubes. He noticed that a nearby fluorescent screen glowed even when the tube was covered and not aimed directly at it, revealing a penetrating form of radiation. The discovery quickly attracted international attention because X-rays could pass through soft tissue and create images of bones.

Henri Becquerel learned about the work at a meeting of the French Academy of Sciences on 20 January 1896. Because he was already studying phosphorescence, he wondered whether fluorescent substances might emit X-ray-like radiation after exposure to sunlight. He tested uranium salts on photographic plates wrapped in black paper.

Cloudy weather accidentally produced the decisive result. Plates left with uranium salts in a dark drawer still became strongly exposed, showing that the radiation came from uranium itself and did not require sunlight. This observation led to the discovery of spontaneous radioactivity. Becquerel shared the 1903 Nobel Prize in Physics with Marie and Pierre Curie.