After each half-life the count rate is halved.
In going from 2016 to 63 there are 5 half-lives.
If 5 half-lives take 35 days,
each half-life is 35 ÷ 5 = 7 days.
gcsescience.com 19 gcsescience.com
Half-Life - Calculations.
1. If you know the
half-life of a material, you can
calculate
what the count rate will be at some time in the future
(previous
page).
2. 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.
Question. The count rate of a
material is 2016 Bq.
After 35 days it has fallen to 63. What is
the half-life?
Answer. Put the count rate in
boxes and use arrows to represent the half-life.
After each half-life the count rate is
halved.
In going from 2016 to 63 there are 5
half-lives.
If 5 half-lives take 35
days,
each half-life is 35 ÷
5 = 7
days.
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