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Becquerel (Bq), equivalent to s^-1, is the SI derived unit of radioactivity (A). 1 Bq is defined as the number of times a nucleus decays every second.

${\displaystyle A={\frac {-dN}{dt}}=\lambda N}$

where ${\displaystyle N}$ is the number of radioactive atoms in a radioactive sample, which has no unit, and ${\displaystyle \lambda }$ is the decay constant measuring how fast radioactive decay occurs over time, which depends on the nature of the radioactive sample, particularly the constituent isotopes.^[1]

The half-life is the time required for half of the radioactive atoms of a sample to decay. It can be found by the simple formula

${\displaystyle t={\frac {0.693}{\lambda }}}$. ^[1]

A petabecquerel corresponds to 10¹⁵ times a Bq. The unit is named in honor of French physicists Henri Becquerel.

• Curie
• Sievert
• Atomic orbital
• Atomic physics
• Particle physics
• Nuclear physics
• Quantum mechanics
• Classical mechanics
• Nuclear binding energy
• Mass-energy equivalence

1. ↑ ^{1.0 1.1} "Decay constant | Definition, Formula, & Facts". Britannica. Retrieved December 1, 2024.