Euygene Thomas Young

                                                       Euygene Thomas Young (1773-1829)

Born on 16 June, 1773, Euygene Thomas Young will always be know for his study on the human ear, the human eye, how it focuses and on stigmatism. His research on colour vision. Working on human ears and eyes, he dedicated much time to the speed of sound and light. He knew that if two sound waves of equal intensity reached the ear 180⁰ out of phase, they cancelled out each other’s effect and no sound was heard. It occurred to him that a similar interference effect should be observed with two light beams, if light consisted of waves. This led young to devise an experiment, now commonly referred to as the young’s double-slit experiment.

In his later years, young devoted most of his time deciphering the Egyptian hieroglyphics found on the Rosetta stone discovered in the Nile Delta in 1799. 

                                      

C.V. Raman

                                                                    C.V. Raman (1888-1970)

Chandra shekhar  Venkat Raman is the only Indian naational to receive Nobel prize (1930) in physics till date. His love for physics was so intensse that he resigned his job of an officer in Indian finance department and accepted the post of Palit Professor of Physocs at the Department of Physocs, Calcutta University. His main contributions are : Raman effect on scattering of light, molecular diffraction of light, mechanical theory of bowed strings, diffraction of X-rays, theory of musical instruments and physics of crystals.
As Director of Indian Institute of Science, Bangalore and later as the founder Director of Raman Research Institute, he did yeoman's to Indian science and put it on firm footings in pra-independence period.
1. Blue Colour of the Sky: we know that scattering of light by air molecules, water droplets or dust particles present in the atmosphere can be explained in accordance with Rayleigh's law. The shorter wavelengths are sscattered more than the longer wavelengths. Thus, the blue light is scattered almost six times more intensely than the red light as the wavelength of the blue light is roughly 0.7 time that of the red. the scattered light becomes rich in the shorter wavelengths of violet, blue and green colours. On further scattering , the violet light does not feach observe's eye as the eye is compartatively less sensitive to violet then blue and other wavelengths in its neighbourhood. So when we look at the sky far away from the sun, it appears blue.
2. White colour of the clouds: the clouds are formed by the assembly of small water drops whose sixe becomes more than the average wavelength of the visiible light (5000A). These droplets scatter all the wavelengths with almost equal intensity. The resultant scattered light is therefore white. So, a thin layer of clouds appears white.

3. Red colour of the sun at sunrise and Sunset: we are now able to understand the red colour of the sun at sunrise and sunset. In the morning and evening when the Sun is near the horizon, light has to travel a greater distance through the atomosphere. The violet and blue wavelengths are scattered by dust particles and air molecules at and angle of About 90⁰ . Thesunlight thus becomes devoid of shorter wavelengths and the longer wavelenght of red colour reaches the observer. so the sun appears to us as red.

George Westtinghouse

                                                       George Westtinghouse(1846-1914)
If ac prevails over dc all over the world today, it is due to the vision and efforts of George Westinghouse. He was an American inventor and enterpreneur having about 400 patents to his credit. His first invention was made when he was only fifteen year old. He invented air brakes and automatic railway singls, which made railway traffic safe.
When Yugoslav inventor Nicole Tesla (1856-1943) presented the idea of rotating magnetic field, George Westinghouse immediatesy grasped the importance of his discovery. He invited Tesla to join him on very lucrative terms and started his electric company. The company shot into fame when he used the energy on Neagra falls to produce electricity and use it to light up a town situated at a distance of 20km.

Michael Faraday

                                                          Michael Faraday (1791-1867)

 British experimental scientist Michael Faraday is a classical example of a person who became great by shear hard work, perseverance, lover for science and humanity. He started his carrier as an apprentice with a book binder, but utilized the opportunity to read science books that he received for binding. He sent his notes to
Sir Humphry Davy, who immediately recognized the talent in the young man and appointed him his permanent assistant in the Royal Institute.

Sir Humphry Davy once admitted that the greatest discovery of his life was Michael faraday. And he was right because Faraday made basic discoveries which led to the electrical age. It is because of his discoveries that electrical generators, transformers, electrical motors, and electrolysis became possible.

Ander Marie Ampere

                                                         Ander Marie Ampere(1775-1836)

French Physisict, mathematician and chemist. Ampere v a child prodigy. He mastered advanced mathematics at the age of 12. A mix of experimental skills and theoretical acumen, Ampere performed rigorous experiments and presented his results in the form of a theory of electrodynamics, which provides mathematical formulation of electricity and its magnetic effects. Unit of current is named in his honour. Lost in his work and ideas, he seldom cared for honours and awards. Once he forgot an invitation by emperor Nepoleon to dine with him. His gravestone bears the eqitaph : Tendun felix (Happy at last). which suggests that he had to face a very hard and ungappy life. But it neber lowered his spirit of creatibity.

Gustav Robert Kirchhoff

                                                       Gustav Robert Kirchhoff(1824-1887)

The fundamental contributions of German physicist Kirchhoff were in the fields of black body radiation and spectroscopy. But he also contributed in many other fields. his rules that you will study in this lesson enable us to analyse complex electric networks. Whit the help of Bunsen spectrum analysis, he discovered elements Rubidium and Cesium. Two Rules of Gustav Robert Kirchhoff. we know that Ohm's law give current-voltage relation for resistive circuits. But when the circuit is complicated, it is difficult to know currrent distribution by Ohm's law. In 1842, Kirchhoff formulated two rules which enable us to know the distribution of current in complicated electrical circuits or eelectrical networks
Rules one: It states that the sum of all currents directed towards a junction (point) in an electrical network is equal to the sum of all the currents directed away from the junction.

Rules Two: This rule  is an application of law of conservatio of energy for electrical eircuits. It tells us that the algebrac sum of the products of the currents and resistances in any closed loop of an electrical network is equal to the algebraic sum of electromotive forces acting in the loop.
While using this rule, we start from a point on the loop and go along the loop either clockwise or
anticlockwise to reach the same point again. the product of current and resistance is taken as positive when we traverse in the directio of current. the e.m.f is taken positive when we traverse from negative to positive electrode thruough the cell. Mathematically,

Alessandro, Conte Volta

                                                      Alessandro, Conte Volta (1745-1827)

                                                          The 100 Most Influential Scientists

Born at Como , Italy, Volta was a professor at Pavia for more than 20 years. A well travelled man, he was known to many famous men of his times. He decisively proved that animal electricity observed by luigi Galvani in frog muscles was a general phenomenon taking palace between two dissimilar metals separated by acidic or salt solutions. On the basos of this observation, he invented first electro-chemical cell, called voltaic cell. The unit of potential difference is named volt in his honour.

                                              

PS Carl Friedrich Gauss

                                                                                Carl Friedrich Gauss ( 1777-1855 ) 

 A German genius in the field of physics and mathematics, Gauss has been one of the most influential

mathematicians. He contributed in such diverse fields as optics, electricity and mathematical analysis.

           As child prodgy, Gauss corrected an error in his father’s accounts when he was only three year old. In      primary school, he stunned his teacher by adding the integers in to 100 within a second.








Though the shun interanctions with scientific community and disliked teaching, many of his students rose to become top class mathematicians – Richard Dedekind, Berhard Riemann, Friedrich Besses and sophie Germain are a few among them. Germany issued three postal stamps and a 10 mark back note in his honour. A carter on moon called gauss crater, and asteroid 100 called Gaussia have been named after him.

Physician scientists

                              Many more scientist of physics they are given below.
                                         Charles Augustin de Coulomb ( 1736-1806 )

A French physicist, Coulomb started his career as military engineer in West Indies. He invented a torsional balance and used it to perform experiments to determine the nature of interaction forces between charges and magnets. He presented the result of these experiments in the form of Coulomb’s law of electrostatics and Coulomb’s law of magneto statics.

 The SI unit of charge has been named in his honour. He also did research on friction of machinery, on windmills, and on the elasticity of metal and silk fibres. By measuring the angle through which the rod twisted, Coulomb could measure the repulsive forces. The coulomb, a unit of electric charge, was named in his honour. He is best known for formulating columb’s low.