比结合能计算器
计算原子核中每个核子的平均结合能。
活度
192,540,883,488.874 Bq
Activity vs Number of Radioactive Atoms (N)
公式
Radioactive Activity
Activity is the rate of radioactive disintegrations per second. One Becquerel (Bq) equals one disintegration per second.
Formula
A = lambda × N = (ln2 / t½) × N
where lambda is the decay constant and N is the number of radioactive atoms. The older unit Curie: 1 Ci = 3.7 × 10¹⁰ Bq (the activity of 1 gram of Ra-226).
计算示例
10¹⁵ atoms of an isotope with half-life 3600 seconds (1 hour).
- 01lambda = ln(2) / 3600 = 1.925 × 10⁻⁴ s⁻¹
- 02A = 1.925 × 10⁻⁴ × 10¹⁵ = 1.925 × 10¹¹ Bq
- 03A = 1.925 × 10¹¹ / 3.7 × 10¹⁰ = 5.20 Ci
常见问题
What is the practical difference between Bq and Ci?
Bq is the SI unit (1 disintegration/second). Ci is the traditional unit (3.7 × 10¹⁰ Bq). Medical doses are often in MBq or mCi. Environmental levels are in Bq/kg or pCi/L.
How many atoms are in 1 Ci of a substance?
N = A / lambda = 3.7 × 10¹⁰ × t½ / ln(2). For Tc-99m (t½ = 6h): N = 3.7 × 10¹⁰ × 21600 / 0.693 = 1.15 × 10¹⁵ atoms, which is about 0.2 nanograms.
Does specific activity depend on isotope?
Yes. Specific activity (Bq/g) = lambda × NA / M, where NA is Avogadro number and M is atomic mass. Short-lived isotopes have enormous specific activity. Carrier-free isotopes have the maximum specific activity.
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