# leah pipes dating - Radioactive dating time change

Carbon dating can only be used to find the age of things that were once alive, like wood, leather, paper and bones.

We’re going to see what 'half-life' means and why radioactivity changes with time. It doesn’t depend on the size of the sample and it doesn’t change with time. So we imagine going in forward one half-life at a time from ZERO years: 10 years, 20 years, 30 years, etc.

We’ll also see how carbon dating can be used to date ancient remains. If we had a bigger sample of the same isotope then the count would be higher, say 200 becquerels. Then we halve the count for each half-life: 100 Bq after 10 years; 50 Bq after 20 years; 25 Bq after 30 years So we can see the radioactivity would be 25 becquerels afer 30 years.

We can use the same idea to find out how long it would take for a sample with radioactivity 120 Bq to drop to 30 Bq. We can use radioactive decay to calculate the age of things.

The best-known technique is called ‘radiocarbon dating’ or just 'carbon dating'.

As it's produced carbon-14 reacts with oxygen to form carbon dioxide and some of it is taken in by green plants and made into sugars along with the 'normal' carbon.

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