The becquerel is the derived unit of radioactivity in the International System of Units ( SI ), symbolized Bq and equal to one disintegration or nuclear transformation per second. Reduced to base SI units, 1 Bq = 1 s -1 . The becquerel is named after Antoine Henri Becquerel, the French physicist credited with the discovery of radioactivity. In the 1970s, the becquerel replaced the curie as the standard unit of radioactivity.
The becquerel is a small unit. In practical situations, radioactivity is often quantified in kilobecqerels (kBq) or megabecquerels (MBq), where:
1 kBq = 1000 Bq = 10 3 Bq
1 MBq = 1000 kBq = 1,000,000 Bq = 10 6 Bq
Thus, 1 kBq is the equivalent of 1000 disintegrations per second (10 3 s -1 ), or an average of one disintegration per millisecond, and 1 MBq is the equivalent of 1,000,000 disintegrations per second (10 6 s -1 ), or an average of one disintegration per microsecond.
Also see International System of Units ( SI ).