Limitations of using carbon dating forum for dating advice
Even though carbon-14 causes around half of the internal radioactivity of living things, it’s only around 0.25 Bq per gram.A common way to isolate the carbon is to carefully burn a piece of the wood and use the carbon dioxide given off.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'.An equilibrium is reached whereby about one in a trillion carbon atoms in the atmosphere is carbon-14.Carbon-14 in living things decays all the time but is replaced by carbon-14 in food. In fact, all living things are rearranged food and NOTHING else.It's useful because it has a half-life of the order of a minute and a pure sample can be prepared simply by shaking a bottle of liquid.
We need to make sure that we’re only measuring the beta radiation from the carbon-14.
Carbon-14 is produced in the upper atmosphere by cosmic rays.
It is a beta emitter with a half-life of about 5600 years.
This means a human adult has a radioactivity of around 3000-4000 becquerels due to carbon-14. When a living thing dies the cells are no longer replaced so no new carbon enters it.
The radioactivity of the carbon-14 begins to decrease. By measuring the radioactivity we can tell how long ago the living thing died.