| Copyright© by TutorVista.com. | ||
Humans have always been curious about the world around them. The world has an astonishing variety of materials and bewildering diversity of life and behaviour. The inquiring and imaginative human mind has responded to the wonder and awe of nature in different ways. This human endeavour led, in course of time, to modern science and technology.
The word science originates from the Latin word 'scientia', meaning 'to know'. The knowledge which man has gained through observations and experiments, when organised systematically, is called science. The scientific theory is that which explains natural phenomena.
The branches of science which deal with non-living things are called physical sciences. Examples of physical sciences are physics, chemistry, geology, geography, astronomy, astrology and oceanology.
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.
Physics is a science that is devoted to the study of the nature and natural phenomena.
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:
The recent knowledge (beyond 1900) is termed 'modern physics', consisting of 2 basic theories.
Physics is sometimes called as 'science of measurement'. The acceleration produced by a force for the motion of a body can be known by measuring the magnitude of applied force and mass of the body. Similarly, the distance of a stone covered, when thrown horizontally, can be measured by knowing its initial speed, time taken by it to cover the distance and acceleration in its motion. As told by Lord Kelvin, "If we can measure what we are speaking about and express it in a value, then we know something about it, else our knowledge is limited." So, to understand physics completely, it is necessary to measure quantities like speed, time, mass and force.
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.
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.
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.
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.
The giant astronomical telescopes and radio telescopes have enabled the astronomers to observe planets and other heavenly objects.
Mathematics has served as a powerful tool in the development of modern theoretical physics.
The other sciences like Biophysics, Geology, Heterology and Oceanography and Seismology use some of the laws of physics.