Decaimento radioativo
- Created by
- Renato Passos, Eng. de Software
- Reviewed by
- Renato Passos, Eng. de Software
Last updated: Apr 18, 2026
About this calculator
The radioactive decay calculator helps determine the remaining amount of a radioactive substance after a specific period. It uses the formula N = N₀·e^(−λt), where N₀ is the initial quantity, λ is the decay constant, and t is the elapsed time. This calculation is essential for predicting how a material disintegrates over time.
The decay constant (λ) is related to the half-life (T₁/₂) of the substance, which is the time required for half of the material to decay. The calculator can convert λ to T₁/₂ or vice versa, depending on the input variables. This allows estimating isotope stability or dating archaeological artifacts.
This tool is useful in fields like nuclear physics, medicine (for radiotherapy), and geology (for rock dating). However, it's important to remember that radioactive decay is a random process at the individual particle level but statistically predictable in large samples. Common mistakes include confusing half-life with total decay time or using inconsistent units of measurement.
When using the calculator, ensure that all input values are accurate, especially the decay constant, which varies by element. The results can aid in planning experiments, assessing environmental risks, or understanding astronomical processes. Always refer to specific data for the substance being analyzed for greater accuracy.
Frequently asked questions
What is half-life and how is it related to decay?
Half-life is the time required for half of the initial quantity of a radioactive substance to decay. It is inversely proportional to the decay constant λ, calculated by T₁/₂ = ln(2)/λ.
Can this calculator be used for all radioactive materials?
Yes, as long as you have the correct decay constant or half-life values. The formula is universal, but parameters depend on the specific isotope.
Why might results vary in real experiments?
Radioactive decay is a stochastic process: in small samples, random variations are more noticeable. In large samples, the average aligns with theoretical calculations.
What should I do if I don't know the decay constant?
Consult isotope half-life tables to obtain λ. Many scientific databases provide these values with precision.
How to convert time units in the calculator?
Ensure all time values (t) are in the same unit, such as seconds, minutes, or years, before performing the calculation.