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Transcript of Half life
To know the phenomenon of half life
To complete our work on radiation types
Half life 3
It is not possible to predict when an individual atom might decay. But it is possible to measure how long it takes for half the nuclei of a piece of radioactive material to decay. This is called the half-life of the radioactive isotope.
There are two definitions of half-life, but they mean essentially the same thing. Half-life is the time taken for:
The number of nuclei of the radioactive isotope in a sample to halve
The count rate from a sample containing the radioactive isotope to fall to half its starting level
Different radioactive isotopes have different half-lives. For example, the half-life of carbon-14 is 5,715 years, but the half-life of francium-223 is just 20 minutes.
Half life 2
The nuclei of radioactive atoms are unstable. They break down and change into a completely different type of atom. This is called radioactive decay.
The radioactivity of an object is measured by the number of nuclear decays it emits each second – the more it emits, the more radioactive it is.
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