Half-life and activity Flashcards
1
Q
What can be noted about the decay of nuclei (timing)
A
- We cannot predict when a radioactive isotope would decay as it is completely random
2
Q
What is the activity of a radioactive substance
A
- The overall rate of decay of all of the isotopes in a sample
- The number of decays per second in a sample
3
Q
What is the half-life of a radioactive substance
A
- The amount of time taken or the number of radioactivve nuclei in a sample to halve
4
Q
What happens to the activity of a substance as the number of unstable nuclei decreases and why
A
- The activity of the substance will also decrease
- This is not because the nuclei are decaying more slowly
- This is because there are less overall nuclei to decay
5
Q
What is radioactive activity measured in
A
- Becquerels
- 1 becquerel = 1 decay per second
6
Q
What is radioactivity measured using
A
- Geiger counter
- Records decays per second
7
Q
What is the corrected count rate of a geiger counter
A
- Corrected count rate = count rate - background count
- Measure background count with no source present