Faraday 1791-1867

Discoverer of benzene; inventor of the dynamo; electromagnetic induction.

At the age of 14 he was apprenticed to a London bookbinder and bookseller, a Mr Riebau. Entrance to the scientific world was not easy matter in 1812 but, chance intervened. Sir Humphry Davy, at the peak of his fame in London, was temporarily blinded in the Laboratory of the Royal Institution, and Faraday was recommended to him as an amanuensis by one of Mr Riebau's customers. Thus began Faraday's scientific career.

Faraday's scientific apprenticeship was spent as an analytical chemist, and it was as an analytical chemist that he discovered and described benzene in 1825. In these same years he discovered the first compounds of chlorine and carbon to be described in the history of chemistry.

It was, however, in the field of electricity and magnetism that he did his most important work. In 1831 Faraday wound an iron ring with two coils; one, connected to a voltaic battery, was to create the primary vibration-the iron ring was to concentrate the lateral vibrations from this-and another coil on the opposite side of the ring was to convert these secondary vibrations into another electrical current. Thus, on the 29th August 1831, Faraday discovered electromagnetic induction.

In 1834 Faraday announced his two laws of electrolysis which made explicit the amount of force required; for a given amount of electrical force, chemical substances in the ratio of their chemical equivalents were released at the electrodes of an electrochemical cell. Put another way, chemical affinity was electrical force acting on the molecular level.

In 1837 Faraday made the discovery of specific inductive capacity. In 1838 and 1839 came a radical new definition of the electrical current; it was the vibrations caused by the rapid build-up and break-down of strain in the molecules of good conductors. Insulators were bodies that did not break down easily; conductors could not take much intermolecular strain; electrolytes broke down under strain and were also decomposed by it. Thus a unitary theory of electricity was proposed, based solely on the existence of intermolecular forces.

No matter how he tried , Faraday was unable to detect the intermolecular strain on which his theories rested. In 1845, however, at the urging of a young Scot, William Thomson, later Lord Kelvin, he turned from electrostatic stains to electromagnetic ones-these later being much more powerful. This time he was successful. The magnet, for example, was not a centre of force; it was an object which concentrated the lines of magnetic force through it. Without the surrounding medium, there could be no magnetism. Thus, the real energy of the magnet was in the space around it, not in the iron bar. This was the fundamental idea of Field Theory. It immediately was rejected by most of Faraday's contemporaries-with one significant exception, James Clerk Maxwell. It was Maxwell who was to take this fundamental idea and make it respectable to the mathematical physicists of his day. Faraday died before this could be done.

 

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