Unit : 1

Introduction to physics, Fundamental Mathematicals Concepts and Measurement

Introduction To Physics

1.1. Meaning of Physics

Since the ancient time, the men have been curious to know about the nature and to study the laws of nature. Indeed, the word 'physics' has been derived from a greek word 'Phusis' which means 'Nature'. Whatever we see all around us, is called the Nature. The occurence of day and night, changes in the seasons, motion of celestial bodies etc., are the examples of some natural phenomena. The occurence of day and night, changes in the seasons, motion of celestial bodies are the examples of some natural phenomena. The man has always been trying to study these natural phenomena systematically and logicaly in sequence. In our day to day life, we usually come across new facts about nature. With the progress in science, the curosity to know about the nature, increases. The systematic and logical study of a natural phenomena and the laws along with the knowledge gained by it is called science.

The English word Science has been derived from the word Scientia of Latin language which means 'to know'. The word Vigyan of Sanskrit language also means 'specific knowledge'. In fact, science is as old as the human kind is. In the development of science, there has been the contribution of all the countries of world like India, Egypt, China etc.

For the sake of convenience of study, science can be divided into several branches such as Physics, Chemistry, Zoology, Botany, Astronomy, Mathematics etc. Physics is that branch of science in which we study the nature and the natural phenomenon. The word Physics has been derived from a Greek word 'Phusis' which means 'Nature'. The equivalent word for nature in Sanskrit is Bhotiki. It is very difficult to define Physics. But on the of its applicability, we can define it as follows:

Physics is that branch of science in which we study the general properties of different states of matter (solid, liquid and gas), different forms of energy and their mutual transformations, internal structure of matter, mutual force of interaction between particles of matter and mutual transformation between the matter and energy.

Matter—Substances which occupy space, have mass and they can be felt by our senses (sight, smell, hear, touch and taste). Such substances are known as matter. For example, air, water, soil, brick, stone, wood, iron etc., are all matter.

Energy- Energy neither has mass, nor does it occupy space. It can only be felt by our senses and it is present in everything in the universe. The existence of energy is in many forms like mechanical, thermal, light, sound, electric, magnetic, nuclear, chemical etc. Energy is the capacity to do work. Therefore, the energy can be measured by the work it can do.

According to Einstein, matter and energy are interconvertible, i.e., matter can be converted into energy and energy can be converted into matter. A mass m when converted into energy E, the energy obtained is given as:

E = mc² ...(1.1)

where c is the speed of light in a vacuum (= 3 × 10⁸ m s^-1). This equation is called the Einstein's mass-energy relation. For the sake of convenience, Physics is divided in the following branches :

Mechanics and General Properties of Matter,

Heat and Thermodynamics,

(iii) Light

(iv) Sound,

(v) Magnetism,

(vi) Electricity and Electrodynamics, and

(vii) Modern Physics.

Modern Physics is further divided into : (a) Atomic and Nuclear Physics, (b) Quantum Physics, (c) Particle Physics, (d) Electronics, (e) Solid-state Physics, (f) Condensed matter Physics and (g) Nano Physics

Nowadays Physics is studied by dividing it in two parts: (i) Classical Physics and (ii) Modern Physics. In classical physics we study the macro systems or the macro properties. Mechanics, Heat and thermodynamics, Light, Sound, Magnetism, Electricity and Electrodynamics, they all come under this. On the other hand, in modern physics we study the micro systems or the micro properties. In this, we consider the Atomic and nuclear physics, Quantum physics, Particle physics, Electronics, Solid-state physics, Condensed matter physics Nano physics.