Final answer:
Wilhelm Roentgen discovered x-rays using a cathode ray tube and a screen coated with barium platinocyanide, leading to the creation of the first X-ray image and earning him the Nobel Prize in physics.
Step-by-step explanation:
When Wilhelm Roentgen discovered x-rays, he was using a cathode ray tube (CRT) and a screen coated with barium platinocyanide. Roentgen's discovery was groundbreaking in the field of medicine and science. He placed objects between the CRT and the coated screen, observing that the mysterious rays could penetrate various substances and leave an impression on photographic film. This process created the first X-ray image of his wife's hand, marking the birth of a new type of imaging that could see through the human body. Roentgen received the Nobel Prize in physics in 1901 for his significant work with x-rays.