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Half life
The rate at which an unstable nucleus decays depends only on what type of nucleus it is. This decay is a random process. This means that if we take a sample of unstable nuclei we cannot know when any individual nucleus is going to decay.
However we can measure what we call the half life (written as T or t1/2) for the element in the sample.


The half life of an element is defined as:
(a) The average time taken for half the original number of nuclei in a sample of an element to decay
(b) The average time taken for the activity of a radioactive source to fall to one half of its original value

The decay constant land half life
Decay constant (l) = 0.693/T
 
 
 
© Keith Gibbs 2009