Physics

Physics and technology derived using the knowledge of Physics has several applications

• Understanding of thermodynamics allows us to use fuels like petroleum, natural gas, which power our cars, aeroplanes, ships. We also generate the power needed for our industries using coal and petroleum fuels.
• Understanding of electro-magnetism has helped us generate electricity. We cannot imagine our modern civilization without electricity. All our home appliances and many of the industrial machines use electricity.
• Understanding of Mechanics leads to the development of many of our vehicles. Ships would not have been possible if we did not understand buoyancy, cars would not be possible if we did not understand friction and aeroplanes were not possible if we did not understand Bernoulli’s principle.
• Understanding of modern physics allows us to develop diodes and transistors. These are the core components of all our electronic equipment like mobile phones, televisions, computers.
• Understanding of nuclear physics allows us to generate electricity from radioactive materials like Uranium. Such elements also find application in medical fields, for example, in the treatment of cancer and in diagnosing certain diseases.
• Many of the engineering branches depend primarily on knowledge of Physics: mechanical, civil, mining, production, etc.

History of Physics

The development of Physics started in Greek philosophies. Aristotle tried to explain everything in the universe with the concept of “cause” rather than just Divine Intervention. Another famous Greek mathematician laid the foundation of fluid statics. We all have heard of the famous “Archimedes Principle of Buoyancy” and the story that goes with the discovery of this principle. The major areas of this time were Astronomy, Mechanics, and Fluid Statics.
Middle ages in Europe revolutionised Physics. Great personalities like Copernicus, Galileo changed the popular belief that Earth was the centre of the Universe. They, along with Kepler in later times, proved using experimental data that Sun was the centre of the solar system and their model could explain the motions of Sun, planets, and the Moon as observed from the Earth. This changed the perspectives of several young minds. One of these was a brilliant mind, Sir Isaac Newton. He discovered the Laws of Motion and Law of Gravitation. To explain these, he developed a new branch of mathematics Calculus. His contribution can be judged by the fact that he is considered to be the most influential scientist of all time.
Some of the major names associated with physics in modern times are Wilhelm Rontgen and Marie Curie for work in the field of radiation, Albert Einstein for his work in the field of relativity, Max Planck, and De Broglie for dual nature of matter. From India, Satyendra Nath Bose helped develop Bose-Einstein Statics as a subdivision of Quantum mechanics. Sir C V Raman received the Nobel Prize for his work in the field of light scattering.

Scope of Physics

A student has several career options after studying Physics at the senior secondary level.

Physics involves study of two fundamental constituents of the universe: Radiation and Matter or it can be regarded as that subject which deals with the study of matter, energy and their interactions. In Physics we not only observe physical events, taking place in our day to day life, but also find out definite mechanisms from the series of systematic observations.
• Research: Research in the pure scientific discipline of physics. For this, you need a B.Sc. and M.Sc. in Physics. A Ph.D. is also sometimes required for some posts. A person can become a scientist or professor through this option. Some of the popular subjects of research currently are quantum physics, superconductivity, relativity.
• Engineering: This is related more to the application of physics. Engineering Physics is the engineering stream that specifically deals with the subject of Physics. A student who has studied Physics along with Maths can join any other stream of engineering as well which includes computer, electrical, electronics, aeronautical, mechanical, chemical, civil, etc. These lead to several different careers like coding, manufacturing, production, designing, architect, teaching. One can also join the Engineering Services of Central (Indian Engineering Service) and State governments. Engineering at masters and Ph.D. levels also include research.
• Medical: Students opting for Biology along with Physics can join any medical school to become a doctor, lab technician, pharmacist, drug tester, dietician, etc.
• General: one can go for any of the career options open to all streams like Defence Forces, Civil Services, M.B.A., etc.

Working with Physics

In Physics, we attempt to explain diverse physical phenomena in terms of a few concepts and laws. One should not think that everything can be proved with physics and mathematics. All physics and also mathematics, is based on assumptions. For example, the universal law of gravitation proposed by Newton is an assumption, which he proposed out of his ingenuity. Before him, there were several observations, experiments and data, on the motion of planets around the sun, motion of the moon around the earth, pendulums, bodies falling towards the earth etc. Each of these required a separate explanation, which was more or less qualitative. Universal law of gravitation cannot be proved. It can be verified and substantiated by experiments and observations.
Physics is a basic science which has influenced all other sciences and has contributed to their progress. Even a prevalent theory of physics may have to be rejected if it is not fit on new experiments or observations. According to Physicist, a scientific theory is a set of systematic ideas that helps to explain a natural phenomenon or the behaviour of natural system on the basis of the established laws of nature. The technique of physics involves Observation, Hypothesis, Testing of the hypothesis and the Final theory.

1. Observations: During any experiment, the scientist identifies all the physical quantities involved in that particular phenomenon, which he wants to study. Observations should be correct so that other scientists also get the same result during same experiment.
2. Hypothesis: The observations are then suitably represented in the tabular form or graphically. On the basis of known scientific laws, a working model is prepared for the tabular data. This working model is called the hypothesis.
3. Testing the hypothesis: On the basis of working model, predictions are made regarding the behaviour of the natural phenomenon under consideration. Testing of predictions are done by taking new observations.
4. Final Theory: If the predictions are verified experimentally, the hypothesis becomes the final theory otherwise hypothesis is modified suitably to test it further and further.

Branches of Physics

The scope of Physics is very wide. It covers a vast variety of natural phenomena. It includes the study of mechanics; heat and thermodynamics; optics; waves and oscillations; electricity and magnetism; atomic and nuclear physics; electronics and computers etc. For the simplicity, it can be classified in number of branches. Some main branches of physics are as follow:

• Heat and thermodynamics
• Mechanics and properties of matter
• Sound or acoustics
• Electricity and Magnetism
• Optics
• Modern Physics
• Nuclear Physics
• Astrophysics
• Biophysics, etc.

Each branch has further sub-branches. For example, Modern Physics is further divided into Atomic Physics, Electronics, Particle Physics, Statistical Physics, Quantum Physics, etc.

Theories of Physics

Most of the areas of facts are well explained by the theories of Physics. There are five main theories which explains the maximum part of the physics.

• Theory of Relativity: It explains the invariance in nature and also the motion of particles which moves as fast as light.
• Classical Mechanics: It explains the motion of particles which travel with velocities much less than that of light.
• Thermodynamics: It is the theory of heat, temperature and conversion of one form of energy into other. It also explains the behaviour of systems containing very large number of particles.
• Quantum Theory: It explains the behaviour of atomic and subatomic particles.
• Electromagnetism: It is the theory of electric as well as magnetic behaviour of particle including optical and radiation of matter.

India’s Contributions towards Physics

Ancient Indian scientist Maharshi Kanad, Acharya Aryabhatta and Acharya Bhaskaracharya have given a new philosophic insight towards physics.
Maharshi Kanad was one of the earliest proponents of the atomic theory of matter and was famous to explain all the worldly happenings in terms of atoms.
Acharya Aryabhatta was the one of the genius scientist of ancient India who not only suggested the rotation of Earth as the cause of day and night and revolution of earth as the cause of changes in season but also had an idea of the force of gravity much earlier than Newton.
Acharya Bhaskaracharya was a mathematician extraordinary who set the rules for calculating location of astronomical bodies any time. His methods of calculation are in use in some parts of India even today.

Mission Chandrayan – I, Mission Chandrayan – II and launching so many satellites through a single launcher by ISRO shows the endless efforts and vision of the modern Indian scientists. In modern times also there are many talented Indian Physicist and inventors who have shown their knowledge in different areas of Physics.

• Prof. C. V. Raman: Nobel Laureate in 1930 for his Raman Effect.
• Dr. Jagadish Chandra Bose: Pioneer in the investigation of radio and microwave optics.
• Dr. Satyendra Nath Bose: He is best known for his collaboration with Albert Einstein in formulating a theory related to the gas like qualities of electromagnetic radiation.
• Prof. Homi Jehangir Bhabha: He is best known as the chief architect of the Indian Atomic Energy Program.
• Dr. Subrahmanyan Chandrasekhar: Nobel Laureate in 1983 for his research on the evolutionary stages of massive stars.
• Prof. Meghnad Saha: Astrophysicist who developed the Saha equation, which explains chemical and physical conditions in stars.
• Dr. A.P.J. Abdul Kalam: He is known for his crucial role in the development of India’s missile and nuclear weapons programs.

Physics in Daily Life

Technology is the application of the principles of physics for the manufacture of machines, gadgets etc. and improvements in them, which leads to better quality of our daily life. We use devices based on principle of physics every day. Some of examples of these are as follow:

1. Different types of Engines (steam, petrol, diesel etc.) are based on the laws of thermodynamics.
2. Mobile phones, calculators and computers are based on the principles of electronics.
3. Means of communication e.g. radio, telephone, television etc. are based on the propagation of electromagnetic waves.
4. Nuclear reactors – are based on the phenomenon of controlled nuclear fission.
5. Generation of electricity is based on the principle of electromagnetic induction.
6. Jet aeroplanes and rockets are based on Newton’s second and third laws of motion.
7. X–rays, ultraviolet rays and infrared rays are used in medical science for diagnostic and healing purposes.
8. Lasers are based on the phenomenon of population inversion and so on.

Contributions of physicists from the world

• Archimedes (Greece) – Principle of buoyancy; Principle of the lever.
• Galileo Galilei (Italy) – Law of inertia,
• Christiaan Huygens (Holland) – Wave theory of light.
• Isaac Newton (U.K.) – Universal law of gravitation; Laws of motion; Reflecting telescope.
• Michael Faraday (U.K.) – Laws of electromagnetic induction.
• James Clerk Maxwell (U.K.) – Electromagnetic theory; Light-an electromagnetic wave.
• Heinrich Rudolf Hertz (Germany) – Generation of electromagnetic waves.
• J.C. Bose (India) – Ultra short radio waves.
• W.K. Roentgen (Germany) – X-rays.
• Marie Sklodowska Curie (Poland) – Discovery of radium and polonium.
• Albert Einstein (Germany) – Explanation of photoelectric effect; Theory of relativity.

According to the Great Men…

• Science is not just a collection of laws, a catalogue of unrelated facts. It is a creation of human mind, with its freely invented ideas and concepts. – Albert Einstein
• We know very little, and yet it is astonishing that we know so much, and still more astonishing that so little knowledge can give us so much power. – Bertrand Russel
• The really created by modern physics is indeed, far removed from the reality of the early days. – Albert Einstein
• Science is the ever unfinished quest to discover all facts, the relationship between things and the laws by which the world runs. – Gerald Holton
• The most incomprehensible thing about the world is that is it comprehensible. – Albert Einstein