Units of Radioactivity
The standard unit in radioactivity is curie (c) which is defined as that amount of any radioactive material which gives 
disintegration’s per second (dps), i.e.,1c = Activity of 1g of 
The millicurie (mc) and microcurie (mc) are equal to 
and 
curies i.e. 
and 
dps respectively.
;
; 
But now a day, the unit curie is replaced by rutherford (rd) which is defined as the amount of a radioactive substance which undergoes 
i.e., 
. The millicurie and microcurie correspondingly rutherford units are millirutherford (mrd) and microrutherford (mrd) respectively.
However, in SI system the unit of radioactivity is Becquerel (Bq)
1 Bq = 1 disintegration per second = 1 dps = 1mrd, 
, 