R6 - Half Life Flashcards
What happens to a sample of radioactivity over time?
It decreases
What happens each time an alpha or beta or gamma particle is given out?
One more radioactive nucleus has disappeared
What happens as the unstable nuclei all disappears?
The activity as a whole decreases as the older the sample gets, the less radiation it will emit
What is the problem with trying to measure how quickly the activity drops off?
It varies for some isotopes and the activity never reaches zero which is why we use to idea of a half life
What is a half life?
The time it takes for half of the radioactive atom to decay
What does a short and long half-life means?
Short half life - activity falls quickly because lots of nuclei decay quickly
Long half life - activity falls more slowly because most of the unstable nuclei dont decay for a long time
How can you measure the half life of a sample using a graph?
Can only be done by talking several readings of a source activity usually using a Geiger-Muller detector
How is the half life found from a graph?
Find the time interval on the bottom axis corresponding to a halving of the activity on the vertical axis
What should you do with the background radiation that also enters the GM detector?
First measure the background radiation then subtract it from every reading you get
