Physics P6

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Different types of radiation:
There are 3 types of radiation. These are alpha, beta and gamma. At
least one of these forms of radiation is released when an unstable
nuclei (isotope) is decaying. Each nucleus has a half-life – the time
taken for half of the radioactive nuclei present to decay.
There is also background radiation, which doesn’t harm us as it is
very lowly reactive. It comes from: natural radioactive materials
(e.g. in the air, soil, living things and rocks), space (cosmic rays
and energy that is emitted by the Sun) and radiation from human
An alpha particle is a helium nucleus (it has 2 protons and 2
neutrons) so it is positively charged (2+). Alpha particles are
emitted when isotopes (unstable nucleuses – in this case, ones that
have too many protons) are decaying e.g. Uranium 235. It is the most
ionizing and least irradiating form of radiation.  This is because the
particles can be easily stopped from entering the body. For example,
it can be blocked by paper. Even our body can protect us from alpha
particles as the skin consists of many layers that can block the alpha
particles and stop them from entering the body. Once in the body, the
cells are completely destroyed and the person becomes highly
In actual fact, alpha particles can be used in smoke detectors.
Radioactive americium releases alpha radiation, which ionises the air
inside the detector. Smoke from a fire absorbs alpha radiation,
altering the ionisation and triggering the alarm.
A beta particle is an electron so it is negatively charged (-). Beta
particles are emitted when isotopes (unstable nucleuses – in this
case, ones that have too many neutrons) are decaying e.g. Carbon 14,
which has 2 extra neutrons.  It is the second most ionizing and second
most irradiating form of radiation. It can be blocked by thin
There are benefits to beta radiation as it can be used in
manufacturing in order to monitor the thickness of materials such as
paper, plastic and aluminium. The thicker the material, the more
radiation is absorbed and the less radiation reaches the detector.
A gamma ray is an electromagnetic wave so it doesn’t have a charge
because it is a form of energy. Gamma rays are emitted after a nucleus
has given out alpha or beta particles as extra energy generated when
decaying. It…


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