Modern Physics
Half-Life
The time required for half of the radioactive nuclei to decay.
Variables
t1/2s
Half-life
Allowed values: greater than 0
λs⁻¹
Decay constant
Allowed values: greater than 0
Your notes
0/5000
Check value
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- λ = 2 s⁻¹ (Decay constant)
Result: t1/2 = 0.34657359 s
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 Radioactive Decay Law and before Activity.
- 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 Half-Life formula?
Half-Life is written t_½ = (ln 2)/λ ≈ 0.693/λ. The time required for half of the radioactive nuclei to decay. It belongs to Modern Physics, under Nuclear Physics.
What are the units in t_½ = (ln 2)/λ ≈ 0.693/λ?
In SI units, t_½ is half-life, measured in s; λ is decay constant, measured in s⁻¹.