P7 - Radioactivity Flashcards
How can you measure radioactivity?
In Becquerels and you use a Geiger counter to measure it
What can stop alpha radiation?
Paper, skin or a few centimetres of air
What can stop beta radiation?
Thin aluminium or a few metres of air
What can stop gamma radiation?
Very thick lead (can partially stop it)
What is alpha radiation?
A fast helium nucleus
What is beta radiation?
Very fast electrons
What is gamma radiation?
High-energy EM waves
Order the ionisation ability of gamma, beta and alpha radiation from least to most ionising
Gamma, Beta, Alpha
When is radiation released?
When large unstable nuclei break down to become more stable
How do you calculate activity (in bq)?
Number of decays / time taken (s)
Why does radiation decrease over time?
Because the number of radioactive nuclei fall and there are less left to decay
What is a half-life?
Time taken for the radioactivity (unstable nuclei) in the sample to fall by half
What are some uses of radioactivity?
Detecting water pipe leaks, smoke alarms, thickness monitoring, carbon dating, uranium dating, medicine, gamma imaging
What is the half-life of Carbon 14?
5700 years
What is nuclear fission?
The splitting of large unstable nuclei, the splitting releases energy
