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James Clerk MAXWELL

James Clerk Maxwell 1831 - 1879

 Automatic translation  Automatic translation Updated June 01, 2013

James Clerk Maxwell was a Scottish physicist and mathematician, born June 13, 1831 in Edinburgh, Scotland. A brilliant student in college, James Clerk Maxwell is studying mathematics at Cambridge University.
He obtained a chair of Natural Philosophy at Aberdeen at the age of twenty-five years. From 1860 to 1865 he served as professor at King's College London.
Following five years of teaching, he decided to retire to his estate Glenair, Scotland.
In 1871 Maxwell was appointed director of the Cavendish Laboratory that has just founded the Duke of Devonshire. It will then cease to develop this laboratory so that it becomes the center of the most illustrious scientific training. Early in his career, Maxwell is interested in gas dynamics.
After proving mathematically that the rings of Saturn are composed of discrete particles, he studied the velocity distribution of gas molecules (according to Gauss' law).
In 1860, it shows that the kinetic energy of these molecules depends only on their nature. But it was his research in electromagnetics of Maxwell which one of the most famous scholars of the nineteenth century. Based on the work of Faraday, in 1862 he introduced the concept of field. Then he shows that a magnetic field can be created by the variation of an electric field.
His teaching is purely mathematical so enable it to develop the well-known differential equations describing the nature of electromagnetic fields in space and time. He explains in his Treatise on Electricity and Magnetism published in 1873.
While developing the theories of electromagnetism, Maxwell also defines light as waves in the electromagnetic and opens the way for other research physicist Heinrich Rudolph Hertz as.


For his fundamental research in thermodynamics, Maxwell designed the famous thought experiment of Maxwell's demon.
It shows that electricity and magnetism could be unified into a single phenomenon, electromagnetism.
He showed that electric and magnetic fields travel through space as waves at a speed of about 300 000 km/s, equivalent to the speed of light.
He has hypothesized that light was a form of electromagnetic radiation. Albert Einstein said of him: "The theory of relativity owes its origin to Maxwell's equations of the electromagnetic field."
Maxwell codified the earlier work of Michael Faraday, André-Marie Ampere and others concerning electricity and magnetism and collected in a set of twenty differential equations.
The theory of electromagnetism Maxwell contained the germ of relativity. Later, Oliver Heaviside theory simplified by reducing to four the number of equations needed. It is these equations that are now known under the name of Maxwell's equations.
Maxwell's laws describe the behavior of electric and magnetic fields and the relationship between the two, namely electromagnetism.
James Maxwell says, "The speed of electromagnetic waves is nearly that of light... which gives a good reason to conclude that light is somehow itself, an electromagnetic disturbance that propagates under the laws of electromagnetism."
The validity of this suggestion was demonstrated later by the experiments of Hertz, which led to the invention of radio, usually attributed to Marconi.
In 1860, Maxwell discovered that it was possible to make color photographs using filters red, green and blue. He was awarded the Rumford Medal that year. James Clerk Maxwell died on November 5, 1879.

 James Clerk Maxwell

Image: "The speed of electromagnetic waves is nearly that of light... which gives a good reason to conclude that light is somehow itself, an electromagnetic disturbance that propagates under the laws of electromagnetism."
James Clerk Maxwell

Maxwell's demon


James Clerk Maxwell imagined a box containing a gas, with two compartments (A and B) P separated by a door at the molecular level.
The daemon controls the door. The operation of the door does not spend energy.
Maxwell assumed that the gas consists of molecules in motion. The demon is able to determine the speed of the molecules, and controls the opening and closing the door according to the state of molecules.
In its original version of Maxwell, the temperature is higher in the compartment B that it is in the compartment A.


Now the temperature is proportional to the mean square speed of molecules. The demon lets through the compartment B to compartment A, molecules slower than the average of the compartment A, and passes from A to B molecules faster than the average speed in B.
Result: the temperature in B increased while that of A decreased. So we cooled a heat sink from a hot source, what the second law of thermodynamics forbids.
It is therefore possible using the information possessed by the devil, to transform the kinetic energy of thermal agitation, in labor.

 Maxwell's demon
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