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Radioactive decay follows exponential decay law. The decay rate depends on the decay constant and the number of remaining nuclei.
公式
The calculator applies N(t) = N₀ × e^(-λt) or A(t) = A₀ × e^(-λt)
- N
- N₀ × e^(-λt) or A(t) = A₀ × e^(-λt) — N₀ × e^(-λt) or A(t) = A₀ × e^(-λt)
- A
- A₀ × e^(-λt) — A₀ × e^(-λt)
ステップバイステップガイド
- 1Enter initial activity or mass, decay constant (or half-life), and elapsed time
- 2The calculator applies N(t) = N₀ × e^(-λt) or A(t) = A₀ × e^(-λt)
- 3Results show remaining nuclei or activity
解いた例
入力
N₀ = 1 mol (6.022 × 10²³), λ = 0.693/5730 yr⁻¹ (¹⁴C), t = 5730 yr
結果
N ≈ 0.5 mol (50%)
One half-life
避けるべきよくある間違い
- ✕Using decay constant instead of half-life without converting
- ✕Assuming linear decay instead of exponential
よくある質問
Can radioactivity be accelerated or stopped?
No, decay rate is determined by nuclear physics and cannot be changed by temperature, pressure, or chemistry.
What's the difference between activity and amount?
Amount is number of nuclei (decreasing exponentially); activity is decay rate (also decreasing, at same rate).
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