Becquerel
Definition

1 Bq = 1 s

A special name was introduced for the reciprocal second (s) to represent radioactivity to avoid potentially dangerous mistakes with prefixes. For example, 1 μs would mean 10 disintegrations per second: (10 s) = 10 s, whereas 1 μBq would mean 1 disintegration per 1 million seconds. Other names considered were hertz (Hz), a special name already in use for the reciprocal second, and fourier (Fr; after Joseph Fourier). The hertz is now only used for periodic phenomena. While 1 Hz refers to one cycle per second, 1 Bq refers to one event per second on average for aperiodic radioactive decays.

The gray (Gy) and the becquerel (Bq) were introduced in 1975. Between 1953 and 1975, absorbed dose was often measured with the rad. Decay activity was given with the curie before 1946 and often with the rutherford between 1946 and 1975.
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