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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.
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Radiation what is it? 
