Starter Question:

1

• Starter Question
• Caesium-126 has a half life of 1.64 minutes.
• Calculate the decay constant in units of s-1.
• ii) If the sample contains 1012 atoms initially,
  what is the initial activity?
• iii) How many atoms will remain after 5mins?
  What will the activity be at this point?
• iv) The sample is observed after some time and
  only 1010 atoms remain. How much time has passed?

2

• Starter Question
• Caesium-126 has a half life of 1.64 minutes.
• Calculate the decay constant in units of s-1.
• 7.0410-3 s-1
• ii) If the sample contains 1012 atoms initially,
  what is the initial activity? 7.04 x 109 Bq
• iii) How many atoms will remain after 5mins?
  What will the activity be at this point?
• 1.211011 atoms remaining, activity of 8.5x108 Bq
• iv) The sample is observed after some time and
  only 1010 atoms remain. How much time has
  passed?
• 654 seconds elapsed.

3

• Starter Question
• Caesium-126 has a half life of 1.64 minutes
• Calculate the decay constant in units of s-1.
• If the sample contains 1012 atoms initially, how
  many will be left after 5mins?
• iii) The sample is observed after some time and
  only 1010 atoms remain. How much time has
  passed?

4

• Starter Question
• Caesium-126 has a half life of 1.64 minutes
• Calculate the decay constant in units of s-1.
• 7.0410-3 s-1
• If the sample contains 1012 atoms initially, how
  many will be left after 5mins?
• Atoms remaining 1.211011 atoms
• iii) The sample is observed after some time and
  only 1010 atoms remain. How much time has
  passed?
• Time passed 654 seconds