Activity & Decay Flashcards

All 5 cards in this deck

What is the activity of a radioactive source?

The number of nuclear decays per second.

What is the unit of activity of a radioactive isotope?

The becquerel (Bq); 1 Bq = 1 decay per second.

How does the activity of a radioactive source change over time?

It decreases, because fewer undecayed nuclei are left; it halves every half-life.

What shape is a graph of activity against time for a radioactive source?

A decay curve – steep at first, then gradually levelling off, never quite reaching zero.

True or false? The activity of a source falls by the same number of becquerels each second.

False. It falls by half each half-life, so the drop per second gets smaller as activity decreases.