Half-Life Flashcards

All 4 cards in this deck

Define the half-life of a radioactive isotope.

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

How do you express the net decline in a radioactive emission after $n$ half-lives as a ratio?

e.g. after 3 half-lives

Final : initial $= 1 : 2^n$.

After 3 half-lives this is $1 : 8$.

How do you find the half-life from a graph of activity against time?

Find the time taken for the activity to fall to half its starting value. That time is the half-life.

Compared with a source that has a long half-life, how does the activity of a source with a short half-life change?

It drops much faster, so the source falls to a low level of activity within a short time.