Radioactive activity and the becquerel
The key idea
Activity is the expected number of nuclear decays per unit time. Its SI unit, the becquerel, equals one decay per second.
Why it matters
Activity depends both on how many unstable nuclei are present and on their decay constant: A = λN.
A picture to remember
Activity depends both on how many unstable nuclei are present and on their decay constant: A = λN.