Using Half-life to Calculate the Count Rate.
Calculations using Half-life.
There are two types of calculation using half-life.
1. If you are given
two count rates and you know
how long it takes to get from one to the other,
then you can calculate the half-life of the material.
The method for this is shown on the next page.
2. If you know the half-life of a
material, you can
calculate what the count rate will be at some time in the future.
The method for this is shown below.
How Half-life can be used to Calculate the Count Rate.
The half-life of a material is 3 hours.
If the initial count rate is 544 Bq,
what will the count rate be after 15 hours?
Put the count rate in boxes and use arrows to represent the half-life.
We are told that the half-life of the material is 3
In 15 hours there are 15 ÷ 3 half-lives
= 5 half-lives.
After each half-life the count rate is halved.
After five half-lives the count rate is 17 Bq.
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