Radioactive
Decay at 16+ |
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All radioactive decay occurs in such a way as the number of atoms 'decaying' in unit time (dN/dt) is directly proportional to the number of undecayed radioactive atoms present in the sample at that time (N).
The mathematics of statistics applies (a very large
number of 'events' needs to be considered). A constant of proportionality
l (called
the decay constant) replaces the proportionality symbol, thereby making
the equation simpler:
or Let us follow the mathematics of this through
for a half life value:
A similar calculation can be done to find the time
taken for a certain percentage of a sample to decay. The half-life of cobalt 61 is 100 minutes. How long does it take for the activity of the sample to fall to 80% of its initial value?
The half-life of radioactive zinc is 50 hours. Find the percentage loss of activity which occurs for a sample each hour. |
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