1. Today’s lesson
Use the term half-life in simple calculations, including the use of information in tables or decay curves.
Give and explain examples of practical applications of isotopes.

2. Nihalanitis

3. ½ - life This is the time it takes half the nuclei to decay
Number of nuclei undecayed
A graph of the count rate against time will be the same shape
time
half-life (t½)

4. ½ - life This is the time it takes half the nuclei to decay
Number of nuclei undecayed
A graph of the count rate against time will be the same shape
time
half-life (t½)

5. Different ½ - lives Different isotopes have different half-lives
The ½-life could be a few milliseconds or 5000 million years!
Number of nuclei undecayed
time
half-life (t½)

6. Example

7. Example
A sample of a radioactive isotope of half life 2 hours has a count rate of counts per second. What will the count rate be after 8 hours?

8. Summary of so far

9. Uses of radioactive isotopes

10. NOT nuclear power!

11. Subtitles
On a double page can you write and underline the following subtitles (there are 6 of them)
Tracers
Killing microbes/sterilisation
Thickness control
Smoke detection
Checking welds
Dating

12. Used as Tracers

13. Used as Tracers

14. Used as Tracers

15. Killing microbes

16. Thickness control

17. Thickness control

18. Smoke detection

19. Checking welds

20. Carbon dating

21. Summary sheet

22. Reading – Pages

23. Can you use these pages to MAKE NOTES on the uses of radioactivity?
Reading – Pages
Can you use these pages to MAKE NOTES on the uses of radioactivity?

24. “Can you………?”

25. Test!
Tuesday 19th March (11B)
Wednesday 20th March (11A)

26. Can you answer the questions on pages 261 and 265?