Radioactive Decay Activity — the NEET Physics formula with its derivation, variables, validity constraints and worked solver.
Radioactive Decay Activity Applicable to radioactive decay processes in samples containing a large number of atoms where statistical laws apply. Rate of decay -dN/dt is proportional to N: -dN/dt = N By definition, Activity A = -dN/dt, so A = N Integrate dN/N = - dt to get N = N 0 e (- t) Substitute N into A = N to get A = N 0 e (- t) = A 0 e (- t) Requires a statistically significant number of nuclei Only valid for spontaneous nuclear disintegration Activity is often confused with the number of nuclei N, but activity is the rate of change of N. The decay constant is sometimes confused with the half-life; they are inversely proportional. Activity is not constant and decreases over time for a specific sample.