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Alpha particles are helium nuclei and do not penetrate far into materials. They
have a mass of 4 and a charge of +2.
· Beta particles are electrons and they penetrate moderately. They have a mass
of 1 and a charge of -1.
· Gamma Rays are EM waves and they penetrate very deeply. They have a mass
and charge of 0.
· Isotopes are atoms with a different number of neutrons.
· Information such as sounds and pictures are converted into electrical signals, it
is then sent on EM waves. There are two types, analogue and digital.
· Analogue signals vary and the amplitude and frequency can take any value.
However, digital are either on or off, which provides a far better quality of
· Half life is the average time taken for half of the radioactive material present
to decay.
· You need a long half-life for devices that have to last, for instance sterilising
machines have to use gamma rays with a long half life. Also, I smoke detectors
(when alpha is used)
· Beta or gamma is used in medical tracers because they can penetrate the skin,
and get back out. Where as alpha cant once it enters the body!
· There are many theories about the Universe: the big bang, genesis, string
theory and the big crunch.
· Light from other galaxies is being red shifted away. Red shift is when a object
moves away from the light and it moves towards the red part of the spectrum.
· The frequency of galaxies that are moving away have a lower frequency than
that closer.
· A star is formed by dust and gas gathering due to gravity. As the mass
increases, so does the gravity and it starts to get hot. Eventually this triggers a
nuclear explosion and a star is born.
· The death of a small star: when the hydrogen runs out, it expands and becomes
a red giant. (the nuclear reactions stop) this forms a white dwarf and then a
black one.
· The death of a large star: the hydrogen runs out and a red super giant is
formed. Then it collapses into a supernova, this then forms into a neutron star.
Then a pulsar or black hole.…read more


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