Radioactive Decay Law and Activity

If `N` nuclei remain: dN/dt = −λN where `λ` is the decay constant. Solving gives: N=N₀e⁽-λt) where: `N₀` = initial number of radioactive nuclei. Activity `R` or `A_r` is: **R = −dN/dt Therefore: R=λN Initial activity: R₀=λN₀ Thus: R=R₀e⁽-λt)**

Activity is measured in: **becquerel (Bq) 1 Bq = 1 decay per second**

**dN/dt=−λN N=N₀e⁽−λt) R=λN**