Question

What is meant by activity or decay rate? Give its unit.

Answer 1

Activity (R) or decay rate which is the number of nuclei decayed per second and it is denoted as

R = `|"dN"/"dt"|`

R = `|"dN"/"dt"|` = λN₀e^-λt 

R = R₀e^-λt

The SI unit of activity R is Becquerel and one Becquerel (Bq) is equal to one decay per second. There is also another standard unit for the activity called Curie (Ci).

1 Curie = 1 Ci = 3.7 × 10¹⁰ decays per second

1 Ci = 3.7 × 10¹⁰ Bq