How carbon 14 test works?

Answer 1

There are several isotopes of carbon. The stable form of carbon is primarily C12.

Comic rays are constantly bombarding the earth, hitting nitrogen14 atoms, and turning them into C14 atoms. The level of C14 in the environment is relatively constant.

So plants grow taking in carbon from the air. Animals grow taking carbon from the plants. At the time all this growing is occurring the ratio of C12 to C14 matches the ratio of C12 to C14 found in the environment.

As time passes more cosmic radiation hits the earth, and the C14 level is maintained at its constant level. And the ratio of C12 to C14 in the environment remains pretty much the same.

However, once that plant or animal stops growing – they stop taking in Carbon. Over time that C14 in the plant of animal decays back into N14. So as time goes on more C14 decays. Young stuff still has most of its C14, old stuff is missing most of its C14(its all turned back to nitrogen). Using the ratio of C12 to C14, we can predict the age of an item.

http://en.wikipedia.org/wiki/Carbon_dating

However carbon dating is not used as a stand alone tool, the stratigraphy of an archeological item is also very important. What events can be identified above and below the position of the item.

Answer 2

Carbon exists in nature as Carbon-12 and -14 in discrete ratios. There are other isotopes, as well. Organisms will take in Carbon in these ratios.
However, when organisms die, they stop taking in Carbon. The Carbon-14 decays and the ratios change at a steady rate. If you know the rate of decay, and the current C-12/C-14 ratio, you can determine the time of death/age.

Answer 3

Carbon-14 is one of the isotopes of carbon element. C-14 is radioactive with half life (time need for decay of half amount) of 5730 years. So you can use this property to do archeological work by comparing the amount of C-14 in the artifacts you have and the fresh plant you find near them. There is a limitation, though. You can only determine the age of an artifact up to 50,000-year-old.

Answer 4

carbon 13 nmr spectroscopy