Modern Physics
Activity
The rate of radioactive decay, measured in becquerels (decays per second).
Variables
ABq
Activity
Allowed values: greater than 0
λs⁻¹
Decay constant
Allowed values: greater than 0
Nunitless
Number of nuclei
Allowed values: greater than 0
A0Bq
Initial activity
Allowed values: greater than 0
Your notes
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Check value
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- λ = 2 s⁻¹ (Decay constant)
- N = 3 (Number of nuclei)
Result: A = 6 Bq
Where this formula is listed
- Modern Physics formulas, under Nuclear Physics, alongside Nuclear Binding Energy, Alpha Decay Energy (Q-value), Beta Decay and Nuclear Radius.
- In the modern physics list it comes after Half-Life and before Nuclear Binding Energy.
- Modern Physics formula sheet, one of 41 formulas printed with symbol keys and SI units.
- The full formula index, grouped by category and topic.
Common questions
What is the Activity formula?
Activity is written A = λN = A₀e^(−λt). The rate of radioactive decay, measured in becquerels (decays per second). It belongs to Modern Physics, under Nuclear Physics.
What are the units in A = λN = A₀e^(−λt)?
In SI units, A is activity, measured in Bq; λ is decay constant, measured in s⁻¹; N is number of nuclei (dimensionless); A₀ is initial activity, measured in Bq.