The activity of a sample is determined in terms of the number of nuclear disintegrations in a second. The Curie or Ci is a common unit for activity measurement. Bq or Becquerel refers to the SI unit for radiation activity measurement.
The activity of K-40 in 70 kg human body is 120 nCi
The relationship between Curie and Becquerel are as follows:
1Ci = 3.7 × 10¹⁰ Bq
1nCi = 37 Bq
Thus, 120 nCi × 37 Bq / 1nCi = 4.4 × 10³ Bq.
Hence, the activity of K-40 in a 70 Kg human body is 4.4 × 10³ Bq .
