Curie
The older unit of radioactivity, defined as the activity of one gram of radium-226.
Formula / equation
1 Ci = 3.7 × 10¹⁰ Bq
Unit
Ci
In depth
Named after Marie and Pierre Curie, the unit is large and inconveniently tied to a specific substance, so it has been superseded by the becquerel. It still appears in older literature and in some medical and industrial contexts.
Examples in the real world
A typical hospital cobalt-60 therapy source rated at several thousand curies.