Who discovered X-rays?

Concept: Landmark discoveries in physics are credited to the scientist who first experimentally observed and documented the specific phenomenon, as recorded in formal scientific history (e.g., Nobel Prize citations and contemporaneous publications) — not merely to someone who worked in a related field.

Application: On 8 November 1895, while experimenting with cathode-ray (Crookes) tubes, the German physicist Wilhelm Conrad Röntgen observed a previously unknown, highly penetrating form of radiation that passed through opaque materials and exposed photographic plates. He called this unknown radiation "X-rays." For this discovery he was awarded the first-ever Nobel Prize in Physics in 1901.

Cross-check (why the other names don't fit):

• Maxwell formulated the mathematical theory unifying electricity, magnetism, and light as electromagnetic waves (Maxwell's equations, 1860s) — decades before X-rays were ever observed, and his contribution was theoretical, not the experimental discovery of X-rays.

• Rutherford is credited with discovering the atomic nucleus and identifying the proton (in the early 1900s-1910s), a separate line of research into atomic structure, not the discovery of X-rays.

• Torricelli is known for inventing the mercury barometer and demonstrating atmospheric pressure and vacuum in the 17th century, an entirely different branch of physics with no connection to X-rays.

Result: The discoverer of X-rays is Röntgen.