Roentgen, REHNT guhn, Wilhelm Conrad (1845-1923), a German physicist, in 1901 won the first Nobel Prize in physics for his discovery of X rays. During an experiment in 1895, Roentgen covered a Crookes tube (an evacuated glass tube through which an electric current was passed) with black paper. He noticed that a dark image appeared on a photographic plate substance near the tube when he turned on the electric current.