Topic 4 Half Life Flashcards
Where does a radioactive substance give out radiation from
The nuclei of there atoms no matter what
What is radiation measured with
Geiger muller tube counter which records the count rate
What is the count rate
The number of radiation counts reaching it per second
What is a half life
Time taken for the number of radioactive nuclei to halve
What can a half life be used for
To make predictions about radioactive sources even though their decays are random
What can half lives be used to find
It’s activity
What is activity
The rate at which a source decays
What is activity measured in
Becquerels bq ( 1bq = 1 decay per second)
What happens each time a radioactive nucleus decays
It becomes a stable nucleus
Why do we use half life
The activity of a source never reaches 0
What does a short half life mean
That the activity falls quickly because the nuclei are very unstable and decay rapidly
Why are sources with a short half life dangerous
Because of the high amounts of radiation they emit at the start but quickly become safe
What does a long half life mean
The activity falls more slowly because most of the nuclei don’t decay for a long time and the source just sits there releasing small amounts of radiation for a long period of time
Why can long half lives be dangerous
Nearby areas can be exposed to radiation for millions of years
Why can’t you predict the exact nucleus in a sample that will decay next
Because radioactive decay is entirely random
