How does radiation occur?

Answer 1

Radiation can mean a variety of things in the literal sense of the word. The 'radiation' of heat is the process of excited particles colliding with each other to give the sensation of heat.

Radiation in the particle sense is the process of a heavy atom (iron or heavier) being too unstable to support its own mass, and therefore it splits itself in to 2 or more smaller atoms. Depending on the size and energy of the particle emitted, radiation can be Alpha (stopped by paper, and not dangerous unless ingested), Beta (can penetrate skin but not bone, dangerous to be near), or Gamma (highly ionising, however can pass through the body).

Usually the particles that are emitted during radioactive decay are small, maybe only one proton. However this can do serious damage if it comes in to contact with DNA, it can rearrange the structure and cause all kinds of mutations in your genetic code. However a large amount of radiation has to be absorbed to get this harmful effect.