Physics Ontology

One map of physics, three ways in. Drill down on any quantity to see its units, the equations it lives in, and how its values span the universe.

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λ\lambda
Quantum

Decay Constant

Probability per unit time that a nucleus will decay.

SI unit

per second (s⁻¹)

Dimension: [ T−1 ][\,T^{-1}\,]

Other units

  • per second (s⁻¹)

Order of magnitude

How values of decay constant span the physical world (in s⁻¹, log scale).

Uranium-238
4.90 × 10-18 s⁻¹
Polonium-214
5.80 × 104 s⁻¹
Lower limit10-20 s⁻¹Upper limit1012 s⁻¹

Appears in 3 equations

Radioactive Decay
N=N0e−λtN = N_0 e^{-\lambda t}
Activity
A=λNA = \lambda N
Half-life and Decay Constant
λ=ln⁡2t1/2\lambda = \dfrac{\ln 2}{t_{1/2}}

Associated scientists

Ernest Rutherford