# Half-Life

Flashcards by Adam Collinge, updated more than 1 year ago
 Created by Adam Collinge over 7 years ago
38
1

Pg101

## Resource summary

 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

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