Calculate radioactive decay. Solve for remaining quantity, elapsed time, half-life, or number of half-lives from the decay formula N(t) = N₀ × (½)^(t/t½).
Optional - fills automatically if half-life is provided.
Half-life (t½) is the time required for exactly half of a radioactive substance to decay. It is a constant characteristic of each radioactive isotope, independent of the amount present.
Mathematically no - each half-life reduces the amount by half, so the quantity approaches but never reaches zero. In practice, once the amount is below detectability (typically after ~10 half-lives), it is considered effectively gone.
The decay constant (λ) represents the probability per unit time that a nucleus will decay. It relates to half-life by λ = ln(2) / t½ ≈ 0.693 / t½. The decay formula can also be written as N(t) = N₀ × e^( - λt).
Radiocarbon dating uses the known half-life of Carbon-14 (5,730 years) to estimate the age of organic materials. By measuring the remaining ¹⁴C ratio compared to atmospheric levels, scientists can determine when an organism stopped exchanging carbon with its environment.