Electromagnetic waves, similar to light waves, are cast out of a tube.
Electromagnetic waves have more power than light waves, so they penetrate the skin.
When the doctor puts the picture up to a light, cracks and breaks become visible. If there was no bone, the x-ray would look all black, since there was nothing to absorb the rays. X-rays help doctors and dentists see your bones. With this technology they can easily and quickly find out what is wrong without causing pain. Physicist Wihelm Roentgen discovered the x-ray in 1895, but even he didn't know what they did other then see through your hand.