Activity of a radioactive sample

The quantity characterizing the amount of aRadionuclide activity according to the frequency of radioactive transformations occurring in it was called Activity.

By the activity of a radioactive sample we mean the number of radioactive nuclei that transform in one second. The activity of the sample decreases exponentially with time, the unit is 1 s -1. This unit is too general, so a resolution was passed in May 1975 that the 1 s -1 unit for activity would be called the becquerel (Bq). A radioactive sample has an activity of 1 Bq if 1 radioactive nucleus is transformed in it in 1 second. The unit of absorbed dose is gray (Gy), the unit of dose equivalent is sievert (Sv).

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