Question

The application of radioactivity as regards carbon dating

Answer 1

Carbon dating is very clever. There is an isotope of carbon called "carbon-14". The amount of this in the atmosphere is constant or thereabouts and (it is assumed) has always been so. When a plant or an animal lives, this isotope is taken in. WHen it dies it stops being taken in. AT this point the amount of it present in the body of the animal or the material of the dead plant starts to decrease and it decreases at a standard rate - half of it is gone in a period we call a half-life. After two half-lives half of the remaining half has gone as well. So if we can measure how much carbon-14 there is in a dead something, we can work out how long ago it died. The half-life of carbon-14 - I have just looked up for you :-) - is 5730 years! So, say we found one-eighth carbon-14 in a dead something. That would mean that 1/2, 1/4, 1/8 = 3 half-lives have come and gone and therefore the something died 3*5730 = approximately 17,000 years ago!