Revise GCSE Physics

Question:What is a laser?

Lasers are sources of Electromagnetic radiation (a light bulb is also a source of electromagnetic radiation). There are visible lasers, infrared lasers and ultraviolet lasers.

**The word LASER is an acronym for Light Amplification by the Stimulated Emission of Radiation.

How lasers work is pretty complicated. The simplest explanation is this: In an ordinary light source all the particles of light (the photons) are produced independently. In a laser the particles of light are produced by copying one particle of light and then copying both copies and then copying the 4 copies and so on in a chain reaction until there are a huge number of identical photons created as a result of this repeated copying process.**