Who discovered X-rays?

It all started as an innocent laboratory experiment, but Professor Wilhelm Conrad Roentgen discovered x-rays back in the 19th century.

In 1895 Wilhelm Roentgen was experimenting with a Crookes tube (a glass bulb emptied of air).  He knew that when an electric current passed between two electrodes in the tube, a cathode ray (stream of electrons) was released, making the tube glow.  He wanted to see what would happen if he covered the tube with a thick black card.

There was a screen painted with luminescent paint standing in the corner of the room, and as soon as the current was switched on it began to shimmer with a greenish-yellow glow, even though the black card had made the tube light-tight.

Reontgen realised this distant glow might have been an unknown type of radiation.  As he was uncertain of what he had discovered, he decided to call the new rays – X-rays and the name stuck.   These are known as invisible  high frequency electromagnetic waves.

Roentgen placed various objects between the tube and screen, and found that the X-rays passed straight through soft materials such as paper, but metal objects were blocked (absorbed) by the rays.

Finally Roentgen aimed the X-ray at his wife’s hand as it rested on a photographic plate.  Not only did the ring on her finger show up sharply, but all the bones of her hand were visible as well.  He’d stumbled on an amazing technique for looking inside the living body without cutting it open.   Roentgen’s discovery revolutionised medicine.