Physics
Nuclei
नाभिक
In Class 12 Physics, this chapter explains the structure and properties of atomic nuclei, including nuclear size, mass number, isotopes, mass defect, and binding energy. Students learn the principles of radioactivity, radioactive decay law, half-life, and mean life, along with the basics of nuclear reactions. The chapter also introduces nuclear fission and fusion, helping students understand how nuclear energy is released and why these processes are important in science and technology.
1Atomic Masses and Composition of Nucleus
परमाणु द्रव्यमान और नाभिक का संघटन
In this Class 12 Physics topic from Chapter 13: Nuclei, students learn how atomic masses are expressed using the unified atomic mass unit and how mass number identifies the total number of nucleons in a nucleus. The topic explains the composition of nuclei in terms of protons and neutrons, links atomic number and isotopes to nuclear identity, and develops the notation used to describe nuclides. It provides a foundation for understanding nuclear size, stability, and later ideas such as mass defect and binding energy.
0 questionsSize of the Nucleus
नाभिक का आकार
In Class 12 Physics, this topic from Chapter 13: Nuclei explains how the size of an atomic nucleus is described and measured. Students learn the nuclear-radius relation R = R₀A^(1/3), where A is the mass number, and understand why nuclear volume is proportional to A. The topic connects this result with nearly constant nuclear density, compares nuclei of different elements, and clarifies the distinction between the tiny nucleus and the much larger atom. It also builds a foundation for understanding nuclear structure and reactions.
0 questionsMass-Energy and Nuclear Binding Energy
द्रव्यमान-ऊर्जा और नाभिकीय बंधन ऊर्जा
In Class 12 Physics, this topic from Chapter 13: Nuclei explains how mass can be converted into energy through Einstein’s mass–energy relation, E = mc². Students learn the meaning of mass defect and nuclear binding energy, calculate binding energy from the mass difference between a nucleus and its separate nucleons, and interpret binding energy per nucleon as an indicator of nuclear stability. The topic also connects these ideas with energy release in nuclear fission and fusion.
0 questionsNuclear Force
नाभिकीय बल
In Class 12 Physics, Chapter 13: Nuclei, students learn how the nuclear force binds protons and neutrons inside the atomic nucleus. They examine its very short range, strong attractive nature at typical nucleon separations, approximate charge independence, and repulsive behavior at extremely small distances. The topic helps explain nuclear stability, saturation of nuclear forces, and why the electromagnetic repulsion between protons does not by itself determine whether a nucleus remains bound.
0 questionsRadioactivity
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.
0 questionsNuclear Energy
नाभिकीय ऊर्जा
This Class 12 Physics topic from Chapter 13: Nuclei explains how energy is released from changes in the atomic nucleus. Students connect mass defect and binding energy with Einstein’s mass–energy relation, then study nuclear fission, fusion, chain reactions, and the basic working of a nuclear reactor. The topic also helps them distinguish controlled and uncontrolled reactions and understand the importance of radiation safety, energy production, and responsible use of nuclear technology.
0 questions