Electromagnetic radiations called X-rays were discovered by Wilhelm Roentgen in 1895 while investigating cathode rays. Cathode rays are electrical discharges inside a tube containing very little air.
Roentgen observed certain crystals lying near the tube that glowed while the tube was working. This was puzzling because the tube was shielded to prevent light from escaping it.
Roentgen deduced that cathode rays hitting the glass of the tube were producing some other rays which made the crystals glow. Further experiments showed that these rays could also pass through solid objects and affect photographic plates. Roentgen used this property to make the first X-ray picture. He was initially reluctant to reveal his discovery to the public, afraid that other scientists may not believe him. Proving his worries baseless, the public wholeheartedly accepted X-rays.
Roentgen discovered their medical use while making a picture of his wife’s hand on a photographic plate using X-rays. The photograph of his wife’s hand was the first photograph of a human body part using X-rays!
Picture Credit : Google