Uses of radiation dating

Since all living organisms on Earth are made up of organic molecules that contain Carbon atoms derived from the atmosphere, they therefore contain Carbon-14 atoms.The Carbon-14 within a living organism is continually decaying, but as the organism is continuously absorbing Carbon-14 throughout its life the ratio of Carbon-14 to Carbon-12 atoms in the organism is the same as the ratio in the atmosphere.We choose a source with a long half-life so that it does not need to be replaced often.Animals and plants have a known proportion of Carbon-14 (a radioisotope of Carbon) in their tissues.The most common tracer is called Technetium-99 and is very safe because it only emits gamma rays and doesn't cause much ionisation.Radiocarbon or Carbon-14 dating is a technique used by scientist to date bones, wood, paper and cloth. It is produced in the Earth’s upper atmosphere when Nitrogen-14 is broken down to form the unstable Carbon-14 by the action of cosmic rays.For geological purposes, this is taken as one year.