Radiation - a-particles.
Particles or waves
which are emitted from a nucleus during decay
are called radiation.
The same word is also used for some
electromagnetic
waves
which have not come from radioactive decay.
An a-particle
(alpha particle) is the same as the nucleus of a helium
atom.
It consists of 2 protons and
2 neutrons. It has a positive
charge.
The positive charge on the a-particle
means that it will be deflected by
a magnetic or electric
field (like the charged droplets in an inkjet
printer).
An a-particle
is deflected less than a b-particle
(because of its bigger mass)
and in the opposite direction (because of its positive
charge).
An a-particle has
by far the most mass of the
three types of
radiation.
It is the most likely to collide
with other atoms which means that
1. a-particles have the
least penetrating ability
and are easily absorbed
by
paper, skin or a few
centimetres of air.
2. a-particles are the
most ionising of the three types of
radiation.
a-particles are
likely to be emitted during the decay of heavy
nuclei
which have a large number of protons and
neutrons
(see examples).
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