A unit used to measure radioactivity. One Becquerel is the amount of a radioactive material that will undergo one transformation in one second. Often radioactivity is expressed in larger units like: thousands (Kq), or millions (MBq) of becquerels. As a result of having one Becquerel being equal to one transformation per second, there are 3.7 x 1010 (37 billion) Bq in one curie