Carbon dating material
Scientists often use the value of 10 half-lives to indicate when a radioactive isotope will be gone, or rather, when a very negligible amount is still left.This is why radiocarbon dating is only useful for dating objects up to around 50,000 years old (about 10 half-lives).Then the radiocarbon dating measures remaining radioactivity.By knowing how much carbon-14 is left in a sample, the age of the organism and when it died can be worked out.Carbon dating was used routinely from the 1950s onward, and it confirmed the age of these historical remains.
Each radioactive isotope decays by a fixed amount, and this amount is called the half-life.
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It is often used on valuable artwork to confirm authenticity.
For example, look at this image of the opening of King Tutankhamen's tomb near Luxor, Egypt during the 1920s.