Because carbon decays at this constant rate, an estimate of the date at which an organism died can be made by measuring the amount of its residual radiocarbon.
Because the cosmic ray bombardment is fairly constant, there’s a near-constant level of carbon-14 to carbon-12 ratio in Earth’s atmosphere.
Organisms at the base of the food chain that photosynthesize – for example, plants and algae – use the carbon in Earth’s atmosphere.
Carbon dating works by comparing the amount of carbon in a sample to the amount of carbon Because organisms stop taking in carbon at death, the age of the material can be precisely determined by this ratio of carbon isotopes.
Carbonwhich is radioactive, is the isotope used in radiocarbon dating and radiolabeling.
A detailed description of radiocarbon dating is available at the Wikipedia radiocarbon dating web page.
Bottom line: Radiocarbon dating is a technique used by scientists to learn the ages of biological specimens from the distant past.If you ever wondered why nuclear tests are now performed underground, this is why.Most radiocarbon dating today is done using an accelerator mass spectrometer, an instrument that directly counts the numbers of carbon-14 and carbon-12 in a sample.Aboveground nuclear testing almost doubled the amount of carbon-14 in the atmosphere. The black arrow shows when the Partial Test Ban Treaty was enacted that banned aboveground nuclear tests. A special kind of radiocarbon dating: Bomb radiocarbon dating.As we mentioned above, the carbon-14 to carbon-12 ratio in the atmosphere remains nearly constant.It’s not absolutely constant due to several variables that affect the levels of cosmic rays reaching the atmosphere, such as the fluctuating strength of the Earth’s magnetic field, solar cycles that influence the amount of cosmic rays entering the solar system, climatic changes and human activities.