Key Theories and Laws of the Physical World
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
Mechanics - We study Newton's laws of motion under mechanics.
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.
FAQs on Physical World in Physics: Complete Guide
1. What does the study of the 'Physical World' in Class 11 Physics introduce a student to?
The chapter on the Physical World for Class 11 serves as an introduction to the vast discipline of physics. It does not focus on mathematical problems but rather on building a conceptual foundation. It explains the scope of physics, the excitement of studying it, the fundamental forces that govern the universe, and the nature of physical laws. This chapter sets the context for all subsequent topics in physics by explaining its connection to technology and society.
2. What is the scope of Physics?
The scope of physics is incredibly vast and is primarily divided into two main domains:
Classical Physics: This deals with macroscopic phenomena. It includes subjects like Mechanics (motion of objects), Electrodynamics (electricity and magnetism), Optics (light), and Thermodynamics (heat and energy). These laws are applicable to objects on a terrestrial or astronomical scale.
Modern Physics: This deals with the microscopic world of atoms, nuclei, and elementary particles. It is based on major theories like Quantum Mechanics, which explains the behaviour of matter and energy at the atomic and subatomic levels, and Relativity, which describes phenomena at very high speeds.
3. What are the four fundamental forces in nature?
The Physical World chapter explains that all forces we observe in the universe are manifestations of four fundamental forces. These are:
Gravitational Force: The force of attraction between any two objects with mass. It is the weakest force but has an infinite range, governing the motion of planets, stars, and galaxies.
Electromagnetic Force: The force that acts between electrically charged particles. It is much stronger than gravity and is responsible for most everyday phenomena like friction, chemical bonding, and light.
Strong Nuclear Force: The strongest of all fundamental forces, but it has a very short range. It binds protons and neutrons together within the nucleus of an atom.
Weak Nuclear Force: This force is responsible for certain types of radioactive decay, such as beta decay. It is stronger than gravity but weaker than the strong nuclear and electromagnetic forces.
4. What is the difference between unification and reductionism in physics?
Unification and reductionism are two principal approaches in the study of physics:
Unification is the effort to explain diverse physical phenomena in terms of a few universal laws or concepts. For example, James Clerk Maxwell unified electricity, magnetism, and light into a single theory of electromagnetism. Similarly, the concept of gravity explains both an apple falling to the Earth and the Earth revolving around the Sun.
Reductionism is the approach of breaking down a complex system into its simpler, constituent parts to understand it better. For example, the study of thermodynamics, which deals with macroscopic properties like temperature and entropy, can be understood by studying the properties of its constituent molecules through kinetic theory.
5. How does understanding the Physical World prepare a student for the chapter on 'Units and Measurement'?
Understanding the Physical World lays the essential groundwork for studying Units and Measurement. The 'Physical World' chapter answers the 'what' and 'why' of physics—what phenomena we study and why they are important. In contrast, Units and Measurements provides the tools for 'how' to study them. By introducing concepts like physical quantities and laws, the first chapter establishes the need for precise and consistent measurement, which is the core theme of the next chapter.
6. How have discoveries in physics led to advancements in technology and society?
Discoveries in physics are fundamental drivers of technological and societal progress. For instance:
The study of electromagnetism led to the invention of radio, television, computers, and all modern communication systems.
Understanding the laws of thermodynamics was crucial for the development of heat engines, which powered the industrial revolution and are essential for vehicles and power plants today.
Research in nuclear physics has led to the development of nuclear power for energy generation and nuclear medicine for diagnostics and therapy.
The development of semiconductor physics gave rise to the transistor, which is the building block of all modern electronics.
7. Why is it important for a student to study the 'Physical World' chapter?
Studying the 'Physical World' is crucial because it builds the scientific temperament and provides a holistic view of the subject. Instead of seeing physics as a collection of isolated formulas and problems, this chapter helps a student appreciate the underlying principles, the elegance of physical laws, and the profound impact of physics on our understanding of the universe. It fosters curiosity and provides a narrative that connects all other chapters, making the study of basic physics more meaningful and less intimidating.
