When a fast moving electron hits a metal, it emits a kind of radiation of unknown nature with high piercing power. This radiation is called X-ray. Not only medical science but also X-rays have various uses in different fields.

 Characteristics of X-rays

1. X-rays run in a straight line.
2. X-ray electromagnetic waves. However, its length is shorter. Wavelengths ranging from about 10⁻⁸ to 10⁻¹² metre
3. X-rays ionize the gas when it passes through the gas.
4. X-rays react with photographic plates.
5. X-rays create florescence in some substances.
6. X-rays can pierce skin, flesh, etc.