In: Physics
Radioactive decay can be used to determine the age of an object.
If you know the number of radioactive nuclei with which an object
started, the number of radioactive nuclei currently present, and
the half-life of the isotope, you can calculate the time since the
object was created.
Suppose an object was created with 4.810×109 nuclei of a
particular isotope that has a half-life of 1.56×103 yr.
At this point in time 9.620×108 nuclei of this
particular isotope remain. What is the age of the object?
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Since the activity (decay rate) of an isotope is proportional to
the number of nuclei, you can use a very similar method to
determine the age of an object using the activity.
Suppose that at the time of creation an object had an activity of
3.820×101 Bq due to a particular isotope that has a
half-life of 2.73×103 yr. At this point in time the
object has an activity of 4.966 Bq due to this particular isotope.
What is the age of the object?
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Number of radioactive nuclei at time is
Decay constant
Number of nuclei at time is
Initial number of nuclei ,
Age of the object is
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Activity of an isotope at time is
Decay constant
Initial activity of isotope
Activity of isotope at time is
Age of object is
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