Thursday, 1 March 2012

7.10 to 7.12 questions

ANSWERS IN BOOK:

7.10 to 7.12 questions

01 February 2012

09:46
1. What happens to the amount of ‘mother’ nuclei as time passes?
2. What sort of radioisotope will decay the fastest - one with a long half life or one with a short half life?
3. Does half life tell us exactly when a particular nucleus in a radioisotope will decay?
4. What are the two definitions of half life?
5. What does the activity of a source mean?
6. What is the unit of activity?
7. What will happen to the number of ‘mother’ nuclei after two half lives?
8. What will happen to the activity of a source after two half lives?

7.10 to 7.12 calculation questions

12 January 2012

10:24
1. A radioisotope has a half life of 12 years. What fraction of the radioisotope will be left after 60 years?
2. If the activity of a sample falls to 1/64th of its original level after 2 hours, what is the half life of the sample?
3. The background radiation in a laboratory is 7 Bq. The count rate from a radioisotope is measured and it has a reading of 119 Bq. If the half life of the radioisotope is 10 minutes, what will be the reading 20 minutes later?
4. Potassium decays into argon. The half life of potassium is 1.3 billion years. A sample of rock from Mars is found to contain three argon atoms for every atom of potassium. How old is the rock?

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