4. Half Life Flashcards
What is half life?
The average time it takes for the number of radioactive nuclei in a sample to halve (decay)
What is activity?
The number of decays every second
What does the unit Bq stand for?
Becquerels
- the unit of activity
How can you measure activity?
With a Geiger muller counter
How do you work out activity?
No. Decays/time (s)
What should you always do when finished with your paper?
Highlight the units and check everything has been converted eg minutes to seconds
Why does radioactivity decrease over time?
The number of nuclei that could decay decreases over time
— as there are fewer nuclei remaining, fewer are able to decay
— therefore the activity also decreases
— the activity halves after every half life
What are the problems in carbon dating an object less than the half life (5730 years) off carbon 14? And what about an object that has an age much larger than this?
1.Too few c-14 nuclei would have decayed
— it would not be possible to measure this
2. Nearly all of the c-14 would have decayed - nothing to measure
