Home Physics Nuclei


Composition and size of nucleus, Radioactivity, alpha, beta and gamma particles/rays and their properties; radioactive decay law. Mass-energy relation, mass defect; binding energy per nucleon and its variation with mass number; nuclear fission, nuclear fusion.

12th physics. NCERT notes

Nuclear Energy

Nuclear Energy Energy then can be released if less tightly bound nuclei are transmuted into more tightly bound nuclei. Two such processes, which we have...
12th physics. NCERT notes

Binding energy per nucleon

As, some mass disappears in the formation of a nucleus in the form of mass defect. This loss in mass reappears in the form...
12th physics. NCERT notes

Gamma Radiations and Gamma decay

Gamma Radiations: There are energy levels in a nucleus, just like there are energy levels in atoms. When a nucleus is in an excited state,...
12th physics. NCERT notes

Beta Particles and Beta Decay

Beta Particles: A nucleus that decays spontaneously by emitting an electron or a positron is said to undergo beta decay. Like alpha decay, this is...
12th physics. NCERT notes

Alpha Particle and Alpha Decay

Alpha Particle: Alpha particles are helium nuclei of nuclear origin. It carries 2 unit positive charges and its mass is about four times the mass...
12th physics. NCERT notes


Radioactivity was discovered by A.H. Becquerel 1896 accidently. Radioactivity was a nuclear phenomenon in which an unstable nucleus undergoes decay. This is referred to as...
12th physics. NCERT notes

Basic Properties of Neutron

Basic Properties of Neutron mn = 1.00866 u = 1.6749 × 10-27 kg A free neutron, unlike a free proton, is unstable It decays...
12th physics. NCERT notes

Atomic Masses

The mass of an atom is very small, compared to a kilogram; for example, the mass of a carbon atom, 12C, is 1.992647 ×...