Radiation what is it?

Radiation is a word given to 'that which emerges or spreads from a central point' - radiates out!

It comes from the Latin: radiare - the word 'radius' comes from that root too!

All rays spread out from a central point (like the radius comes out from the centre of a circle!). They travel in straight lines in all directions. The term 'radiation' is nowadays taken to mean only 'dangerous' rays - ionizing radiation - but it can mean any type.

There are lots of types of radiation but you can fit these into three main categories:

ionizing radiation,

nuclear radiation and

electromagnetic radiation.

Name

Ionising Radiation

Nuclear Radiation

Electromagnetic Radiation

Alpha particles
Yes
Yes
Beta Particles
Yes
Yes
Gamma Rays
Yes
Yes
Yes
X-rays
Yes
Yes
Ultraviolet Rays
Yes (the high energy ones!)
Yes
Visible Light Rays
Yes
Infra Red Rays
Yes
Microwaves
Yes
Radio and TV waves
Yes

Ionizing Radiation

All ionizing radiation has enough energy to free electrons from atoms and molecules. This can have dramatic effects in complex biological molecules like DNA and result in cells dying or malfunctioning (cellular damage). This damage can lead to cancerous growths in organs and mutations in reproductive cells can lead to mutated offspring (systemic biological damage). It is therefore dangerous to you (and all living things).

ALL nuclear radiation is ionizing but to different extents.

Nuclear Radiation

All nuclear radiation comes from the nucleus of an atom. (That is where the name comes from!)

It is spontaneous - we cannot make an atom emit a particle of nuclear radiation. Extreme pressure or temperature has no effect on the rate of decay of a substance.

It is random. We cannot predict how an individual atom will behave, only by using the mathematics of probability can we predict how a proportion of a large number of atoms will behave.

Electromagnetic Radiation

This is made up of 'photons' - little packets of pure energy. It is the name of the 'family' of energy that light belongs to.

Photons have no mass - they are energy not matter.

The higher the frequency of a photon the higher its energy. The only nuclear radiation that is electromagnetic, is the gamma ray as that is the only part of the electromagnetic spectrum that comes from the nucleus.