Activity & Decay Flashcards

All 4 cards in this deck

What is the activity of a radioactive source?

The number of nuclear decays (emissions) per second.

What is the SI unit of activity, and its symbol?

The becquerel, Bq. 1 Bq = 1 decay per second.

True or false? Measured count rate is the same as the true activity of a source.

False. Count rate is only the radiation reaching the detector, and it includes background radiation.

Why does the activity of a radioactive source fall over time?

Each decay leaves one fewer unstable nucleus, so as time passes there are fewer nuclei left that can decay.