More on Half-Life

Question 1

Give one way that radioactivity can be measured or detected.

Answer 1

Using a Geiger-Muller tube or photographic film

Question 2

How many half-lives would it take for the number of nuclei or a radioactive isotope to decrease to 1/8 of its initial value?

Answer 2

3 half-lives

Question 3

The initial activity of a different radioactive sample is 96 Bq. Calculate the activity after four half-lives

Answer 3

6 Bq
After 1 half-life, activity = 96 / 2 = 48 Bq
After 2 half-lives: 48 / 2 = 24 Bq
After 3 half-lives: 24 / 2 = 12 Bq
After 4 half-lives: 12 / 2 = 6 Bq