How does radioactive dating work?
1 Answer
Radioactive dating works by measuring the percentage of a radioactive isotope present in a sample.
Explanation:
If 50% of the radioactive isotope is left one half life has passed. If only 25% of the radioactive isotope is left two half lives have passed.
Divide the percentage in half again 12.5% left three half lives have passed. Again divide it in half 6.25% and four half lives have passed.
For example Carbon 14 has a half life of 5,730 years. If a sample has 6.25 % of the amount of Carbon 14 present in a living sample then four half lives have passed since the sample died and stopped absorbing Carbon.
Carbon 14 has a limited of approximately 50,000 years or less. The percentage of Carbon 14 becomes extremely small and difficult to measure. Also any contamination of the sample can distort the calculation of the age when the percentage is small At 9 half lives
only 1/512 of the Carbon 14 is left. .200 percent.
Most fossils have no Carbon left in them and Carbon 14 and radioactive dating can not be used to date them.
