Whilst plants and animals are alive their Carbon-14 remains constant, but when they die it decreases due to radioactive decay.
The amount, A, of Carbon-14 in an object t thousand years after it dies is given by the formula:
(The quantity A measures the rate of Carbon-14 atom disintegration and this is measured in “counts per minute per gram of carbon” cpm/g)
(a) Using a calculator, draw a table of values to show how the amount of Carbon-14 in an object varies with time. (Correct to 2 decimal places).
(b) Draw a graph of this data.
(c) Imagine that you have a fresh sample of tree wood. What is the rate of Carbon-14 atom disintegration?
(d) Imagine you have a sample of charcoal from Stonehenge and it is 4000 years old. What is the rate of Carbon-14 atom disintegration?
(e) Charcoal from the famous Lascaux caves in France gave a count of 2.34 cpm/g. Estimate the date of formation of the charcoal.
(f) Investigate "half-life" of a radioactive isotope.