- Science word is derived from Latin word ‘Scientia’ which means ‘to know’. Science has many disciplines, Physics being one of them. The word Physics is derived from Greek word ‘Fusis’ meaning ‘nature’. Physics is that branch of Science which deals with the study of matter and energy or matter or motion i.e. Physics is a study of matter and energy in its different forms. In other words, physics is the study of nature and its laws. We expect that all the different events taking place in nature always take place according to some basic rules and revealing these rules of nature from the observed events in physics.
- As physics is a study of nature and its behaviour it is a real science. No one has been given authority to frame the rules. Sir Issac Newton, Einstein are the great physicist because using the observations available at that time, they could guess and frame the laws of physics, which explain these events and the observations in a convincing way. If a new phenomenon is observed which can not be explained using existing laws or rules we are always free to change the rules.
- Knowledge of Physics overlaps with other sciences considerably, hence such overlapping gives rise to subjects like Biophysics, Biochemistry, Astrophysics, Geophysics etc.
- Physics can be conveniently divided into two parts, classical Physics (Pre-1900) and modern Physics (Post – 1900). The classical physics includes the study of mechanics, gravitation, heat, sound, light, electricity and magnetism. The modern Physics includes the study of quantum mechanics, relativity, atoms, molecules, nuclei, elementary particles and condensed matter.
- The study of science and particularly in Physics is based on systematic observation, logical reasoning, model making and theoretical prediction and necessary modifications. All the four steps taken together constitute what we call the ‘scientific method’. The scientific method helps us to describe the given physical phenomenon or behaviour of a physical system in terms of a limited number of laws. This gives us what we call as ‘theory’. Theory should be self-consistent and consistent with known experimental data. The discrepancy between the theory and experimental data has to lead to new theories in Physics.
Relation Between Physics and Mathematics:
- Physics is directly related to maths because the description of nature becomes easy if we have the freedom to use mathematics.
- In physics, we use mathematical techniques like algebra, trigonometry and calculus. Thus mathematics is a language of physics. Without knowledge of mathematics, it would be much more difficult to discover, understand and explain the laws of nature.
- But we should note that mathematics itself is not a physics. To understand nature is a journey of physics, mathematics is the mean of the journey.
Different Branches of Physics:
- Mechanics is a branch of physics, which deals with the motion of material bodies. In this branch, the forces responsible for the producing or changing the motion of the body are studied. The energy involved is also studied. Newton’s laws of motion, the law of conservation of momentum and energy, Newton’s gravitation law forms the base of this branch of Physics.
- Heat is the energy that a body possesses by virtue of the motion of the molecules of which it is composed of and the potential energy due to interatomic forces. The term heat is also used to indicate the energy in the process of transfer between an object and its surroundings because a difference exists between their temperatures. Thermodynamics is the name given to the branch of physics which studies the relationship between heat and mechanics.
- Acoustic is a branch which studies sound. Wave motion is studied in this branch. An object in a state of vibration can set medium particles in the vibration and this disturbance in the medium can travel from one point to another. Thus sound is wave motion itself.
- Optics is a branch of science which studies electromagnetic waves to which the eye responds (light). Propagation of light means the propagation of electromagnetic waves with varying electric and magnetic fields through a vacuum or a transparent medium. It has two broad branches geometric optics and physical optics.
Electricity and Magnetism:
- These topics are interrelated with each other. We have to take help of another topic when we are studying one of them individually. Electricity deals with the forces on charged particles, the effect of such forces. It also studies the phenomenon caused by the motion of charged particles. Magnetism can have an effect on the electric current. magnetic materials can be used in producing electric currents. Electronics is the branch of electricity.
- Modern physics is the branch of physics which deals with the recent developments in the science related with physics such as Radioactivity, X-Rays, Cathode Rays, Atomic and Molecular Structure, Quantum Theory and wave mechanics etc.
Pioneers of Physics
|Name of Scientist||Country||Field / Discovery/Invention|
|Ampere, Andre Marie
(287- 212 B.C.)
(1776 – 1856)
|Italy||Avogadro’s law, Gaseous state|
|Bardeen J.||United States||Transistor|
|United States||Lightning conductor|
Becquerel Henry Antoine
(1700 – 82)
|Sweden||Bernoulli’s principle, working of an aeroplane|
Bohr, Niels Henrik David
(1885 – 1962)
|Denmark||Bohr’s theory of hydrogen atom|
(1882 – 1970)
|Ireland||Study of gaseous state, Boyle’s law|
|Bethe A. H.
|Germany / France||Theory of nuclear reaction|
|Jacques Alexander Cesar
(1746 – 1823)
|England||Study of gaseous state, Charle’s law|
(1831 – 79)
|Compton A. H.
|United States||Compton effect of light|
(1473 – 1543)
|Poland||Earth revolves around the sun|
|Curie, Pierre (1859-1906)
& Marie (1867-1934)
|Poland||Radioactivity, Radium , Polonium|
David Edward Hughes
|England / USA||Microphone|
|de Broglie||France||Wave nature of the electron|
|Edison Thomas Alva||United States||Thermionic emission|
|Germany||Special theory of relativity, Electromagnetic theory of light. Photoelectric effect.|
|United States||Passenger lift|
|France||Internal combustion engine|
|Italy/ United States||Demonstration of the existence of new radioactive elements.|
|England||Laws of electrolysis, electromagnetic induction, dynamo|
|Italy||Laws inertia, simple pendulum, Telescope, Law of falling bodies.|
|Hess Victor Franz||Austria||Cosmic rays|
|England||Elasticity, Hooke’s law|
|Holland||Properties of matter at low temperatures|
|Holland||Wave theory of light|
|Scotland||Condensing steam engine|
|Germany||motion of astronomical bodies, Keppler’s law (Planetary Motion)|
|Lee De Forest
|Marconi G.||Italy||Wireless telegraphy|
|Millikan R. A.||United States||Atomicity of charge, Charge on electron|
|England||Calculus, Laws of motion and gravity|
|Oersted H. C.
Oppenheimer, J. Robert
|Pauli Wolfgang||Austria||Quantum exclusion principle|
|Raman C.V.||India||Scattering of light by molecules|
Robert H. Goddard
|United States||Liquid fuel rocket|
|Roentgen (Röntgen), Wilhelm Conrad
|England||Radioactivity, the structure of an atom|
|Thomson J. J.||England||electrons, Cathode rays|
Wilbur Orville Wright
|United States||Electric transformer|
|Yukawa Hideki||Japan||Theory of nuclear forces|
|Presper Eckert and John W. Mauchly
|United States||Electronic computer|
John Bardeen, W. Brattain, W. Shockley
Important scientific Principles:
|Technology / Instrument/ Machine||Principle|
|Rocket Propulsion||Newton’s second and third law|
|Hydroelectric Power||Principle of conservation of energy|
|Heat Engines||Laws of Thermodynamics|
|Refrigerator||Laws of Thermodynamics|
|Electric Generator||Electromagnetic induction|
|Cyclotron||Simultaneous application of magnetic and electric field|
|Nuclear Reactor||Nuclear Fission|
|Calculators||Digital logic of electronic circuit|
|Computers||Digital logic of electronic circuit|
|Atom Bomb||Nuclear Fission|
|Hydrogen Bomb||Nuclear Fusion|
|Genetic Engineering||Role of DNA in heredity|
|Production of ultra-high magnetic field||Superconductivity|