Basic Physics

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Basic Definition of Physics

Basically, Physics is the knowledge of nature. If we want to understand the matter at miscellaneous levels, let’s say both macroscopic and microscopic levels, basic Physics turns out to be a gold mine to study their nature of motion, behavior in low and high temperatures, the kinetic energy of molecules, and much more.

Physics helps us study the motion, behavior of matter through space and time. On the whole, it is a natural science that deals with all the related entities of force and energy.

Definition of Physics

Physics is a natural science that deals with matter and energy and interactions of matter with one another. It also deals with all physical processes and phenomena of a particular system. 

Let’s suppose that there is a container filled with gas and on the top of this container, a frictionless movable piston is fitted. Now, on passing heat to this system, the gas expands. So, what is the Physics behind this expansion?

Well! When the heat is added, there is a temperature rise in the gas, which leads to the rise in the internal energy of the gas, and that internal energy is the kinetic energy. Initially, these gas molecules had a stored internal potential energy and they gain entropy because this potential energy converts into kinetic energy. This results in the expansion of the gas, and therefore, uplifting of the piston. 

So, what do we infer from the above statement?

Well! Whatever energy was supplied got totally transformed into work, i.e., no wastage of energy. The same scenario is observed in an imaginary engine, viz: Carnot engine.


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So, our first law of thermodynamics (energy is transformed without creating or destroying it) with the help of Physics.

Definitions of Physics

Let’s have a look at a few Physics definition and branches:

1. Forces in Nature

Every day we observe the applications of forces in one or other objects like contact forces between two objects, frictional force between your shoes and the road, forces exerted on strings and springs, viscous forces, electrostatic and magnetic forces and much more; all these forces we encounter at the macroscopic world are manifestations of the following two types of forces:

  • Gravitational forces

  • Electromagnetic forces

However, at the microscopic level, we have two basic types of forces:

  • Strong nuclear forces 

  • Weak nuclear forces

2. Ampere

The unit Ampere was named after a French Physicist and Mathematician named André-Marie Ampère. It is the SI unit of current. 

The International System of units describes ampere in other terminologies by assuming it as the electromagnetic power an electrical circuit holds through which the current is flowing when the conductor is subjected to the potential difference across its ends. The dimensional formula for the current is [A].

Branches of Physics

There is a big list of branches in Physics basic, let’s enlist these:

  • Mechanics

  • Modern physics

  • Thermodynamics

  • Classical physics

  • Electricity

  • Magnetism

  • Geo physics

  • Plasma physics

  • Optics

  • Sound and oscillation

  • Chemical physics

  • Engineering physics

  • Quantum physics

  • Electronics

  • Nuclear physics

  • Particle physics

  • Biophysics

  • Astrophysics

  • Condensed matter physics

  • Solid-state physics

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Let’s discuss the basics of Physics in detail:

Physics Definition and Branches

Physics Branches

Sub-branches of Physics


  • Classical mechanics

  • Kinematics

  • Dynamics

  • Statistical mechanics


  • Nature of heat

  • Heat effects

  • Modes of heat transfer 

Sound and Oscillation

  • To study the physical aspects of sound waves

  • Production of sound

  • Properties and applications of sound


  • To study the physical aspects of light

  • Properties of lights

  • Use of optical instruments

Electricity and Magnetism 

  • To study the charges in rest and in motion

  • Effects of charges

  • The relationship of charges with magnetism

Atomic Physics

  • Structure of atoms

  • Properties of atoms

Nuclear Physics

  • To study the behavior and properties of nuclei and other particles

Plasma Physics

  • To study the production and properties of the ionic state of matter

Geo Physics

  • To study the internal structure of the earth

Classical Physics

Mainly deals with the following:

  • Newton’s laws of motion

  • Laws of Gravitation

  • Maxwell’s kinetic theory

  • Thermodynamics

Main branches of Physics

  • Optics

  • Acoustics

  • Classical Mechanics

  • Electromagnetism

Major subtopics of Classical Physics

Other topics that classical Physics deals with are:

  • Classic Mechanics

  • Thermodynamics

  • The concept of Electromagnetism

Quantum Physics

  • Quantum mechanics

  • Quantum statistics

  • Quantum field theory

  • Quantum electrodynamics

Relativistic Physics

  • Einstein’s field equations

  • The general theory of relativity

  • The special theory of relativity

Modern Physics

  • The theory of relativity

  • Quantum mechanics

Max Planck and Albert Einstein are considered the father of modern Physics.


  • To study the biological problems and phenomena/processes by employing various techniques of Physics

  • Study of D.N.A via Physics 


  • To study the universe and the following things residing in space:

  1. Stars

  2. Planets

  3. Galaxies


A branch of Physics in which the motion of electrons is controlled by semiconductor devices.

Chemical Physics

To study the science of Physical relations indulged in Chemistry

Engineering Physics

To study the field of Physics and Engineering


To study the physical processes and their relationships in the science of Economy

Health Physics

To help workers become aware of the protective measures while working under the radar of harmful radiations.

Mathematical Physics

To be able to apply physical phenomena in mathematical systems

Molecular Physics

  • Structure of molecules

  • Behavior of molecules

  • Properties of molecules

Particle Physics

A high-energy Physics or Particle Physics analyses the following:

  • The behavior of elementary particles

  • Properties of elementary particles

FAQ (Frequently Asked Questions)

1. What Are the Two Main Branches of Physics?

Answer: Physics is the branch of science that deals with the interaction of matter and energy. There are Two Main Branches of Physics, viz: Classical Physics and Modern Physics. There are four sub-branches of Physics that are as follows:

  • Mechanics

  • Optics

  • Electromagnetism

  • Thermodynamics

2. What is the Basic Introduction to Physics?

Answer:  Physics is the observational study of the basic principles that govern the physical world around us. We start our observation with motion first and we learn about the forces, nature of forces, momentum, energy, and many more concepts in different physical situations. There are a plethora of concepts discovering further, as for a subject like Physics, the sky is the limit.

3. What is the Physics Formula Book?

Answer: A Physics formula book is a PDF form of all the formulas for Physics Class 9-12. You can download it from our website, i.e., for free anytime at your convenience.

4. What is the Vector Addition?

Answer: We define vector addition as the addition of two or more vectors. The parallelogram law describes the rule for the vector addition of two or more vectors.