Radioactive Activity
Compute the activity of a radioactive sample, A = λ·N, the product of the decay constant (λ) and the number of radioactive nuclei present (N). Activity, measured in becquerel (Bq = 1 disintegration/s) or curie, expresses how many nuclei decay per second. It is the fundamental quantity quantifying a radioactive source, and it decreases over time as nuclei decay. Enter the decay constant and the number of nuclei.
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Atividade radioativa
A atividade A = λ·N quantifica o quão 'radioativa' é uma amostra: quantos núcleos decaem por segundo. É o produto da constante de decaimento λ (a probabilidade de cada núcleo decair por segundo) pelo número de núcleos radioativos presentes. A unidade SI é o becquerel (1 Bq = 1 desintegração por segundo); a antiga é o curie (1 Ci = 3,7×10¹⁰ Bq, a atividade de 1 g de rádio-226). Como a atividade depende do número de núcleos, ela diminui no tempo à medida que estes decaem — seguindo a mesma lei exponencial, A(t) = A₀·e^(−λt). É a grandeza que aparece nos rótulos de fontes e fármacos radioativos. Informe a constante de decaimento e o número de núcleos.
Related Tools
Gamma Exposure Rate
Compute the exposure (or dose) rate of a point gamma source, X = Γ·A/d², from the exposure-rate constant (Γ, specific to the radionuclide), the source activity (A) and the distance (d). It combines the source strength with the inverse square law, allowing you to estimate the dose received at a given distance — fundamental in planning tasks with radioactive sources. Enter the gamma constant, the activity and the distance.
Radioactive Half-life
Compute remaining amount A = A₀·(1/2)^(t/T) for radioactive decay.
Decay Constant
Compute the radioactive decay constant, λ = ln(2)/T½, from the half-life (T½). The constant λ is the probability of a nucleus decaying per unit time — the larger it is, the more unstable the isotope and the shorter its half-life. It links the half-life (time for half the nuclei to decay) to the activity and to the exponential decay law. Enter the isotope's half-life.
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