Calculate the remaining quantity of a radioactive substance at any point in time. Uses the exponential decay law with any half-life you specify.
๐ Formula
N(t) = Nโ ร e^(โฮปt)
N(t) = Remaining quantity at time t
Nโ = Initial quantity at time zero
ฮป = Decay constant = ln(2) / half-life
t = Elapsed time
e = Euler's number โ 2.71828
โข๏ธ Radioactive Decay Calculator
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What is Radioactive Decay?
Radioactive decay is the spontaneous transformation of an unstable atomic nucleus into a more stable configuration, releasing energy in the form of radiation. The rate of decay is completely random at the individual atom level โ but for large numbers of atoms, the decay follows a precise exponential law.
What is a half-life?
The half-life is the time required for exactly half of the radioactive atoms in a sample to decay. After one half-life, 50% remains. After two half-lives, 25% remains. After ten half-lives, less than 0.1% remains. The half-life never changes โ it is a fixed property of each isotope.
โข๏ธ Carbon dating: Carbon-14 has a half-life of 5,730 years. Living organisms continuously absorb C-14 from the atmosphere. When they die, the C-14 starts decaying. Scientists measure how much C-14 remains to estimate when the organism died โ accurate up to about 50,000 years.