Science is a systematic and organised attempt to acquire knowledge about the surroundings through observations, experiments and verification.
Fig: Newton's Reflector2. Scientific Method
Several interrelated steps are involved in the scientific method. Some of the most significant steps are as follows:
• The systematic observations
• Mathematical modelling
• Theoretical prediction
Physics is a fundamental science concerned with understanding the natural phenomena that occur in our universe. It has many branches such as Mechanics, Electromagnetism, Thermodynamics, Modern Physics, etc.
Between 1600 and 1900, three broad areas were developed, which is together called Classical Physics. These three areas of study are classical mechanics, thermodynamics and electromagnetism. But by 1905 it became apparent that classical ideas failed to explain several phenomena. Then some new theories were developed in what is called Modem Physics such as Special Relativity, Quantum Mechanics, etc.
4. Scope and Excitement of Physics
Fig: This parabola-shaped lava flow illustrates the application of mathematics in physics—in this case, Galileo's law of falling bodies5. Physics in Relation to Other Sciences
Physics is a very significant branch of science which plays a crucial role in understanding the developments pertaining to the other branches of science such as Chemistry, Biology etc.
(i) Physics in relation to Mathematics: Study of physical variables led to the idea of differentiation, integration and differential equation. Meaningful interpretation of Mathematics becomes Physics.
(ii) Physics in relation to Chemistry: The concept of X-ray diffraction and radioactivity has helped to distinguish between the various solids and to modify the periodic table.
Understanding the bonding and the chemical structure of substances is easy with the help of the concept of interactions between various particles.
(iii) Physics in relation to Astronomy: Optical telescopes of reflecting and refracting type enabled man to explore the space around. Discoveries like radio telescopes have revolutionized the study of Astronomy.
(iv) Physics in relation to Biology: The conceptual study of pressure and its measurement has helped us to know blood pressure and hence the functioning of the heart. The invention of X-rays developed the field of diagnosis. Electron and optical microscopic designs have revolutionized the study of medical science.
(v) Physics in relation to Meteorology: The discoveries regarding the study of pressure variations help us to forecast the weather.
Various other inventions of physics have opened new vistas of study in the field of sciences and social sciences.
6. Physics in Relation to Technology and Society:
Advancement in physics has led to new technologies and vice-versa. Sometimes technology gives rise to a new dimension of physics; at other times physics generates new technology.
In fact, technological development is closely related to the application of science and physics in particular. Physics has a dominant influence on society. It has helped the human beings to develop their ideas. Development of digital communication systems, rapid mass transport system, lasers making bloodless surgeries, etc., has made human life easy and pleasant.
There are four fundamental forces in nature that govern the diverse phenomena of the microscopic and macroscopic world. These are :
(i) Gravitational force
(ii) Electromagnetic force
(iii) Strong nuclear force
(iv) Weak nuclear forceFig: Gravitational Force between 2 objects
Table 1.1 Some Physicists from Different Countries of the World and their Major Contributions:
Major contribution/ discovery
Country of Origin
Principle of buoyancy; Principle of the lever
Law of inertia
Wave theory of light
The universal law of gravitation; Laws of motion; Reflecting telescope
Laws of electromagnetic induction
James Clerk Maxwell
Electromagnetic theory; Light-an electromagnetic wave
Heinrich Rudolf Hertz
Generation of electromagnetic waves
Ultra short radio waves
Marie Skłodowska Curie
Discovery of radium and polonium; Studies on natural radioactivity
Explanation of photoelectric effect;
Theory of relativity
Victor Francis Hess
Measurement of electronic charge
Nuclear model of the atom
Quantum model of the hydrogen atom
Inelastic scattering of light by molecules
Louis Victor de Broglie
Wave nature of matter
Controlled nuclear fission
Quantum mechanics; Uncertainty principle
Relativistic theory of electron;
Ernest Orlando Lawrence
Theory of nuclear forces
Homi Jehangir Bhabha
Cascade process of cosmic radiation
Lev Davidovich Landau
Theory of condensed matter; Liquid helium
Chandrasekhar limit, structure and evolution of stars
Transistors; Theory of superconductivity
Unification of weak and electromagnetic interactions
Table 1.2. Progress in the unification of different forces/domains in nature:
Laws of thermodynamics
Controlled nuclear fission
Radio and Television
Generation, propagation and detection of electromagnetic waves
Light amplification by stimulated emission of radiation
Production of ultra-high magnetic fields
Newton's laws of motion
Faraday's laws of electromagnetic induction
Conversion of gravitational potential energy into electrical energy
Bernoulli's principle in fluid dynamics
Motion of charged particles in electromagnetic fields
Reflection of ultrasonic waves
Total internal reflection of light
Thin-film optical interference
Wave nature of electrons
Fusion test reactor (Tokamalt)
Magnetic confinement of plasma
Giant Metrewave Radio Telescope (GMRT)
Detection of cosmic radio waves
Trapping and cooling of atoms by laser beams and magnetic fields.
Table 1.3. Fundamental forces of nature:
All objects in the universe
Weak nuclear force
Very short, Sub-nuclear size (~ 10-16 m)
Some elementary particles, particularly electron and neutrino
Strong nuclear force
size (~10-5 m)
Nucleons, heavier elementary particles
Table 1.4. The link between technology and physics:
Name of the physicist
Achievement in unification
Unified celestial and terrestrial mechanics; showed that the same laws of motion and the law of gravitation apply to both the domains.
Hans Christian Oersted Michael Faraday
Showed that electric and magnetic phenomena are inseparable aspects of a unified domain: electromagnetism.
James Clerk Maxwell
Unified electricity, magnetism and optics; showed that light is tin electromagnetic wave.
Sheldon Glashow, Abdus Salam, Steven Weinberg
Showed that the 'weak' nuclear force and the electromagnetic force could be viewed as different aspects of a single electro-weak force.
Carlo Rubia, Simon
Verified experimentally the predictions of the theory of electro-weak force.
7. Conservation Laws in Physics