Question

How is the half-life of a radioactive material useful for radioactive dating?

Answer 1

The half life of a radioactive element is the period in which it is reduced to half its amount. All organisms have isotope C14 in a roughly fixed proportion. Comparing the current amount of C14 in it with C12, and using the half life period, we can roughly estimate the millenia in which the organism existed. This is how half life of radioactive material is used for radioactive dating.

Here is an example (not to scale, just for understanding the values are random);

If there is 2000 ppm C14 in organisms and only 125 ppm is found. If the half life is a 1000 years, the sample is 4000 years old.