Nuclear Physics

Nuclear physics is a branch of physics that studies the behavior and properties of atomic nuclei. It delves into the structure, composition, and interactions of atomic nuclei, which are the central cores of atoms.

History of Nuclear Physics

Models of atom

Democritus model of atom: 

About 2000 years ago, a Greek philosopher suggested that matter is made up of tiny invisible particles called atoms. The word ‘atom’ comes from a Greek word ‘cannot be cut or divided’.

Dalton’s model of atom:

John Dalton was a scientist who studied gases in the early part of the 19th century. He thought that Democritos is right, that all matter is made up of atoms, he imagined these atoms to be tiny hard spheres. Dalton said that some substances are made up of identical atoms which are called elements.

An important discovery was that atoms of an element always have the same mass. Different elements have atoms with different masses. Each different element has its own type of atom.

Thomson’s plum pudding model:

In 1897, J.J Thomson discovered the electrons and found that the atom itself was made up of smaller particles that we now call sub-atomic particles.

Electron was the first subatomic particle to be discovered. Thomson showed that it was a negative particle of very weight. 

He thought that atom was a ball of positive charge dotted through it. 

Rather like currents in a bun or plums in a pudding. For this reason the thomson,s idea is called plum pudding  model of atom.

Nuclear model of atom or rather ford,s model of atom:

According to this model the atom contains a nucleus of the centre, which contains neutrons and protons and the electrons revolve around the nuclears.

Summary of properties of ionising radiation:-

Radiation	Symbol	Nature	Charge	Ionising power	Range in air	Relative penetration	Stopped by
Alpha	∝	Helium Nuclei	+2	Strong	5-8cm	1	Paper
Beta	β	electron	-1	medium	5m to 10m	100	Thin Alumineum
Gamma	γ	E. m wave	0	weak	Infinity	10000	Thick lead sheet