[Physics Class Notes] on Physical World Pdf for Exam

What is Physics?

Physics is derived from the Greek term, nature. In Sanskrit, the word Physics is equivalent to Bhautiki, which refers to the nature and properties of energy and substance and the study of the physical world or physical world science.

In a more widespread sense, Physics is the study of the basic laws of nature and their manifestation. Similarly, its subject matter includes sound, mechanics, electricity, gravity, heat, light and radiation, magnetism, and the atoms’ structure.

Natural Science – the one that relates to the nature of the physical world or physical world science.

Scope and Excitement of Physics

There are mainly two domains of interest in physics named macroscopic and microscopic.

Macroscopic Domain

It includes the phenomena at the terrestrial, laboratory, and astronomical scales.

Microscopic Domain

It includes molecular, atomic, and nuclear phenomena.

Stil, recently a third domain of interest between macroscopic and microscopic domain (Mesoscopic) has also come into existence. The Scientists’ deals with some tens or hundreds of atoms in this domain, has emerged as an exciting research field.

Theories Related to Physics

Various methods related to the macroscopic and microscopic domain are further categorized as given below.

Classical Physics

It is the macroscopic phenomena study. It includes subjects like

• Electrodynamics – It deals with the magnetic and electric phenomena associated with the magnetic and charged bodies.

• Thermodynamics – It deals with the macroscopic equilibrium systems and is concerned with internal energy changes, entropy, temperature, and more, of the system via the transfer of heat and external work. The efficiency of heat engines and refrigerators and more.

• Optics – The study of phenomena connected with light and optical instruments such as microscope, telescope, and more related things.

Quantum Theory

It is a kind of framework to explain the microscopic phenomena like classical physics cannot explain the phenomenon at a microscopic level (or smaller dimensions such as nuclei, atoms, and more).

Physics, Technology, and Society

There is numerous count of examples in the world which show the close relation between physics, technology, and society as well. Like, in the 18th century, in England, the steam engine is inseparable from the Industrial Revolution, which had a high impact on the human civilization course. Computers and wireless communication technology are a few other examples.

Fundamental Forces in the Nature of the Physical World

The fundamental forces in nature that govern the diverse phenomena of both the macroscopic and the microscopic world are listed below.

• Gravitational Force – It is the force that attracts an object towards the earth.

• Strong Nuclear Force – It is the force that every object produces, repels, or attracts the other objects.

• Electromagnetic Force – It is the force that binds the electrons and protons with the nucleus of the atom.

• Weak Nuclear Force – It is the force that is not strong enough to bind the electrons and protons in an element. Similarly, it only appears in the β-decay of the nucleus.

• Towards Unification of Forces – This category defines how various scientists are grouped into the different forces of nature among a common force.

Basic Properties of Fundamental Forces in Nature

Conservation Laws in Physics

The physical quantities remain unchanged in a process known as conserved quantities.

A few of the general conservation laws in nature include the laws of conservation of mass, energy, angular momentum, linear momentum, charge, parity, and more. But, some conservation laws are true for one fundamental force, not for the other ones.

These conservation laws have an intense connection with the symmetries of nature. Symmetries of space, and time, and other symmetry types play a central role in modern theories of fundamental forces in nature.

Technological Applications of Physics

In the 21st century, physics and its concepts have led to some of the minor and major discoveries. It is also innumerable to think about the amount of work that has been done under Physics. A few examples where Physics has done wonders and has led the discoveries or inventions are as given below.

• In the 19th century, the steam engine, a very popular discovery in the Industrial Revolution, developed in England.

• Sometimes, rather Physics gives rise to new technology. For example, the development of Wireless Communication Technology that followed the basic laws of magnetism and electricity. 

• Meitner and Hahn discovered the phenomenon of neutron-induced fission of Uranium in 1938 that led to the development of weapons and Nuclear Power Reactors. 

• Using the basic laws of Physics, conversion of Wind Energy, Solar Energy, and Geothermal Energy into Electricity is another great discovery.