What is Physics:

The word physics has been derived from the Latin word physica, which means natural thing. Though, there are many definitions of physics, yet it can be defined as “The study of the properties of matter, energy and their mutual relationship is called physics.” According to Microsoft Encarta, “Physics, major science, dealing with the fundamental constituents of the universe, the forces they exert on one another, and the results produced by these forces. Sometimes in modern physics a more sophisticated approach is taken that incorporates elements of the three areas listed above; it relates to the laws of symmetry and conservation, such as those pertaining to energy, momentum, charge, and parity.” It means that physics is the branch of science, which deals with the properties of matter and emery and the relationship between them. It also tries to explain the material world and the natural phenomena of the universe. The scope of physics is very wide and vast. It deals with not only the tinniest particles of atoms, but it also dwells upon natural phenomenon like galaxy, milky way, solar and lunar eclipse etc

BRANCHES OF PHYSICS: 

A branch of physics, which is mainly concerned with the laws of motion and gravitation of Sir Isaac Newton and James Clark Maxwell’s Kinetic theory and thermodynamics, is called classical physics. Classical physics is mainly concerned with matter and energy. In classical physics energy and matter are considered as separate entities. Acoustics, Optics, Classical mechanics and electromagnetics are the traditional branches of classical physics. Moreover, any theory of physics, which is considered null and void in the modern physics, automatically falls under the realm of classical physics.

Classical Physics vs Quantum Physics | Source

Modern Physics

Modern physics is the branch of physics, which is mainly concerned with the theory of relativity and quantum mechanics. Albert Einstein and Max Plank were the pioneers of modern of physics. They were the first scientists who laid down the foundations of modern physics by introducing the theory of relativity and quantum mechanics respectively. In modern physics energy and matter are not considered as separate entities; rather they are considered as different forms of each other.

Nuclear Physics

Nuclear physics is the branch of physics which deals with constituents, structure, behaviour and interactions of atomic nuclei. Encarta dictionary defines the nuclear physics as “the branch of physics in which the structure, forces, and behavior of the atomic nucleus are studied.” In the modern age, nuclear physics has got a very wide scope. It is used in power generation, nuclear weapons, medicines etc.

Nuclear Physics Definition | Source