The word 'Physics' comes from the Greek word 'phusis' meaning 'nature', introduced by the ancient scientist 'Aristotle'. Man has always been fascinated by nature. So, he questioned and sought answers for every phenomena nature could offer. The branch of science which is devoted to the study of nature and natural phenomena is called Physics. It is expected that all the events in nature take place according to some basic laws. Physics reveals these basic laws from day-to-day observations.
The knowledge of physics accumulated till 1900 is called classical physics that deals with macroscopic phenomena. It includes subjects like:
- Mechanics
- Thermodynamics
- Electromagnetism, and
- Optics
The recent knowledge (beyond 1900) is termed 'modern physics', consisting of 2 basic theories.
- Relativity
- Quantum mechanics
Scope and excitement of physics
The scope of physics is very large. Physics deals with a wide variety of disciplines such as mechanics, heat and light. Study of mechanics helps us to know the forces involved in the flight of a bird, walk of a man and so on. The study of heat helps us to know the rise and fall of temperatures, working of heat engines and so on. Electricity helps to understand the basic principles involved in generators and motors. The exciting discipline of modern physics takes us into the microscopic world of atoms and electrons.
The distribution of charges proposed by Thomson in his model was tested by Ernest Rutherford in 1909 by using subatomic projectiles to bombard a target of atoms. These projectiles, called alpha (a) particles, were identified as one of the products of radioactivity.
Rutherford's famous a-particle scattering experiment is represented in the figure above. A stream of high energy a-particles from a radioactive source is directed at a thin foil (thickness-100 nm) of gold metal (having a circular fluorescent zinc sulphide screen round it). Whenever an a-particle strikes the screen, a tiny flash of light is produced at that point.Physics in relation to science, society and technology
Among the various disciplines of science, the only discipline which can be regarded as being most fundamental, is physics.
It has played a key role in the development of all other disciplines.For example,
Physics in relation to chemistry
The study of structure of atoms, radioactivity, X-ray, diffraction, etc., in physics has enabled chemists to rearrange elements in the periodic table and to have a better understanding of chemical bonding and complex chemical structures.
Physics in relation to Biological science
The optical microscopes developed in physics are extensively used in the study of biological samples.
Electron microscope, X-rays and radio isotopes are used widely in medical sciences.Physics in relation to astronomy
The giant astronomical telescopes and radio telescopes have enabled the astronomers to observe planets and other heavenly objects.
Physics related to mathematics
Mathematics has served as a powerful tool in the development of modern theoretical physics.
Physics related to other sciences
The other sciences like Biophysics, Geology, Heterology and Oceanography and Seismology use some of the laws of physics.
Physics related to society and technology
- The development of telephone, telegraph and telex enables us to transmit messages instantly.
- The development of radio and television satellites has revolutionised the means of communication.
- Advances in electronics (computers, calculators and lasers) have greatly enriched the society.
- Rapid means of transport are important for the society.
- Generation of power from nuclear reactors is based on the phenomenon of controlled nuclear chain reaction.
- Digital electronics is widely used in modern technological developments.
