Half-Life

Question	Answer
What does the radioactivity of an object do over time?	Decreases
What is the unit of measuring radioactivity? What does it mean?	Becquerel (Bq) one nucleus decaying per second
What happens when an alpha, beta or gamma ray is given out?	One more radioactive nucleus has disappeared
What is half life?	Half life is the average time it takes for the number of nuclei in a radioactive isotope sample to halve
Why do we have to use the measure of half life to measure how quickly radiation falls of?	The activity never reaches zero
What is the count-rate?	The number of radioactive emissions detected per unit of time
What does a short half life mean?	The radioactive activity falls quickly as there is a lot of quick nuclei decay
What does a long half life mean?	The radioactive activity falls more slowly because most of the nuclei don't decay for a long time
How do you work out the half life of a sample?	Divide the initial number by two until you get the new number. Count how many intervals it took and then divide the time scale (in seconds) by the number of intervals
How do you work out the half life from a graph?	Find the time interval on the bottom axis corresponding to a halving of the activity on the vertical axis

Resource summary

	Created by Adam Collinge over 10 years ago