Particle detection and the decay law
Answers are for parents and teachers.
1
Initially 1200 nuclei; 3 half-lives pass. How many remain?
150
2
A source has activity 640 Bq and T = 4 days. What is the activity after 12 days (Bq)?
80
3
A sample has 12.5 % (1/8) of its original ¹⁴C. What is its age? (T = 5730 years)
17190
4
A counter registered 900 pulses. What is the approximate typical error (√N)?
30
5
Why are isotopes with a short half-life (hours) preferred in medical diagnostics?
Their activity falls quickly after the test, so the patient's dose is small.