The level of radioactive Carbon was measured in organisms that had just died. The samples were then measured after a period of time to find the new levels of radioactivity. The loss of radioactivity was then extrapolated backwards to find the half life.

## How do they know the half-life of carbon-14?

Scientists can determine the age of ancient objects by a method called radiocarbon dating. The bombardment of the upper atmosphere by cosmic rays converts nitrogen to a radioactive isotope of carbon, 14C, with a half-life of about 5730 years.

## How is the half-life of C 14 used to determine the age of substances?

Radiocarbon dating is the process of determining the age of a sample by examining the amount of 14C remaining against its known half-life, 5,730 years. However, when an organism ceases to exist, it no longer takes in carbon from its environment and the unstable 14C isotope begins to decay.

## Why does carbon-14 have a half-life?

Beta Decay Because 14C is radioactive, it decays over time–in other words, older artifacts have less 14C than younger ones. C decays by a process called beta decay. During this process, an atom of 14C decays into an atom of 14N, during which one of the neutrons in the carbon atom becomes a proton.

## What is the half-life of carbon-14?

5700 ± 30 yr Abstract. The half-life of radiocarbon (14C) is 5700 ± 30 yr, which makes it particularly useful for dating in archaeology.

## Will all the carbon-14 eventually disappear?

The half-life of carbon-14 is the amount of time it takes for one-half of the original amount to disappear by radioactive decay. After 50,000 years, a fossil wont have any radiocarbon left in it. Carbon-14 will have all disappeared by radioactive decay.

## What percentage of carbon-14 remains after 3 half-life?

After 1 half-life, 12 of the C-14 would remain. After 2 half-life, 12 of the 12 of the C-14 = 14 of the C-14 would remain. After 3 half-life, 12 of the 14 of the C-14 = 18 of the C-14 would remain.

## What percentage of carbon-14 remains at the third half-life?

Explanation: After 1 half-life, 12 of the C-14 would remain. After 2 half-life, 12 of the 12 of the C-14 = 14 of the C-14 would remain. After 3 half-life, 12 of the 14 of the C-14 = 18 of the C-14 would remain.