# Ncert 12th Physics Chapter-13

## Nuclear Force

The strong forces of attraction which hold together the nucleus in small nuclei of an atom inspite of electrostatic forces of repulsion. From binding energy curve, We have seen that for average mass nuclei, The binding energy per nucleon is approximately 8 MeV, Which is much larger than the binding energy in atoms. Thus, for […]

## Nuclear Energy: Nuclear Fission and Nuclear Chain Reaction

Nuclear Energy: The energy released during a nuclear reaction is called nuclear energy.   Or The energy released during the transformation of nuclei with less total binding energy to nuclei with greater binding energy. The two distinct way of obtaining energy from nucleus are as follows. 1. Nuclear Fission 2. Nuclear Fusion 1. Nuclear Fission: Nuclear

## Nuclear Energy: Nuclear Fusion

Nuclear Fusion: The process in which two light nuclei combine(at extremely high temperature) to form a single heavier nucleus is called nuclear fusion. For Fusion to take place, the two nuclei must come close enough so that attractive short range nuclear force is unable to affect them. Since both the nuclei are positively charged particles,

## Radioactive Displacement Laws

Radioactive Displacement Laws: This Law describes which chemical element and isotope are created during the particular type of radioactive decay. α-Decay:  α-Decay is a process in which and unstable nucleus transforms itself into a new nucleus by  emitting and α particle (A Helium nucleus ₂He⁴). Since an α  particle has two protons and two neutrons, so after an α-Decay,

## Half-Life of Decay and Average Life

Half-Life of Decay: It is defined as the time after which number of atom left will become half of initial number of atom, Then from equation Average Life: It is defined as the total life time of all the atoms of the element and dividing it by the total number of atoms present initially in

Radioactivity: A French physicist H Bequerel discovered radioactivity in 1896 by accident. Radioactivity is spontaneous nuclear phenomenon in which an unstable nucleus undergoes a decay with the emission of same(α,β) and electromagnetic radiations (γ) rays. In nature, three types of radioactive decay occurs which are as- α-Decay: In α decay, a helium nucleus ₂He⁴ is emitted. β-Decay:

## Binding Energy Curve

It is a plot of the binding energy per nucleon Ebn versus the mass number A for a large number of nuclei. From Graph: 1. Average binding energy per nucleon for light nuclei like ₁H¹, ₁H², ₁H³ is small. 2. For mass numbers ranging from 2 to 20, there are sharply defined peaks corresponding to ₂He⁴, ₆C¹²,

## Mass Energy and Nuclear Binding Energy

Mass-Energy: Einstein  showed that mass is another form of energy and one can convert mass-energy into other form of energy.                               E = mc² Where, E=energy, m=mass and c is speed of light. Nuclear Binding Energy: The energy with which nucleons

## Shape, Size of Nucleus and Nuclear Density

Shape and Size of Nucleus: Nuclei are regarded as spherical. The size of the nucleus has been measured with the help of a variety of experiments involving the scattering of particles as neutrons, protons, electrons, etc. From all these experiments, it is found that the volume of the nucleus is directly proportional to the number

## Atomic Number and Mass Number

Atomic Number: Atomic number of an element is the number of proton present inside the nucleus of an atom of the element. It is also equal to the number of electron revolving around the various orbits. Atomic Number Z = Number of protons = Number of electrons(in neutral atom). Mass Number:  Mass of an element

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