Physics

Radioactivity

रेडियोधर्मिता

Radioactivity is the spontaneous disintegration of unstable atomic nuclei, studied in Class 12 Physics under Chapter 13: Nuclei. Students learn how alpha, beta and gamma emissions change a nucleus, and how radioactive decay follows a statistical law. The topic introduces decay constant, half-life, mean life and activity, while connecting them with nuclear stability, conservation laws and mass–energy equivalence. It also helps students interpret decay equations and solve related numerical problems.