Half-Life Flashcards

All 4 cards in this deck

What is the half-life of a radioactive isotope?

The time taken for half the undecayed nuclei to decay, or for the activity of the source to halve.

How do you find the half-life from a graph of activity (or count rate) against time?

Read the starting activity, halve it, and read off the time taken for the activity to fall to that value. That time is the half-life.

True or false? After two half-lives, all of the radioactive nuclei in a sample have decayed.

False. A quarter of the original undecayed nuclei are still left.

True or false? The half-life of a radioactive isotope depends on how much of it you start with.

False. The half-life of an isotope is constant, whatever the starting amount or activity.