Faraday, Michael (1791-1867)

Faraday, Michael (1791-1867)

English physicist and chemist

Michael Faraday's early life had a remarkable resemblance to that of Benjamin Franklin . Faraday was born in Newington, Surrey, England. Like Franklin, Michael Faraday was part of a large family. His father was a blacksmith who lacked the resources to obtain a formal education for his son.

Franklin had been apprenticed to a printer; young Faraday went a similar route, becoming apprenticed to a bookbinder. In each case, this led to a voracious love of books. Michael was especially interested in chemistry and electricity . He studied the articles about electricity in the Encyclopaedia Britannica. His employer not only allowed him to read all that he wanted, he encouraged the boy to attend scientific lectures.

A turning point occurred in 1812. In that year, Faraday obtained tickets to hear the lectures of Humphry Davy at the Royal Institution. Faraday took careful notes extending to 386 pages, which he had bound in leather. He sent a copy to Sir Joseph Banks (1743–1820), president of the Royal Society of London, who wielded great influence over European scientific investigation. Faraday hoped to make a favorable impression, but if Banks ever looked through the book with its carefully drawn and colored diagrams, Faraday never knew it.

Determined not to be ignored, Faraday sent a copy of his notes to Davy and included an application for a job as Davy's assistant. Davy was impressed, but did not offer Faraday work as he already had an assistant. Later, however, after firing the assistant in 1813, Davy contacted Faraday. The job description was not quite what Faraday had in mind. A trustee of the Royal Institution had said, "Let him wash bottles. If he is any good, he will accept the work; if he refuses, he is not good for anything." Faraday accepted, even though it meant he would be paid less than what he was making as a bookbinder.

Shortly thereafter, Davy resigned his post at the Royal Institution, married a wealthy widow, and decided to travel through Europe . Faraday accompanied the couple and met such illustrious men as Italian physicist Alessandro Volta and French chemist Louis-Nicholas Vauquelin.

In 1820, Danish Physicist Hans Christian Oersted amazed scientists with the discovery that electric current produced a magnetic field . Faraday had a greater goal in sight: Oersted had converted electric current into a magnetic force; Faraday intended to reverse the process and create electricity from magnetism . Within a year Faraday, now back in England, constructed a device that essentially consisted of a hinged wire, a magnet and a chemical battery. When the current was turned on, a magnetic field was set up in the wire, and it began to spin around the magnet. Faraday had just invented the electric motor. Faraday's motor was certainly an interesting device, but it was treated as a toy.

At this point, Davy, realizing that Faraday had the potential to eclipse him, jealously claimed that Faraday had taken his own idea for the experiment.

Faraday's first major contribution to chemistry came a few years later. In 1823 he unknowingly became the "father" of cryogenics by producing laboratory temperatures that were below freezing . He discovered how to liquefy carbon dioxide , chlorine, hydrogen sulfide, and hydrogen bromide gases by placing them under pressure, but again Davy took the credit. Two years later Faraday discovered the compound benzene, which became his greatest contribution in chemistry. In 1865 German chemist Friedrich Kekulé was able to determine the structure of benzene, leading to the understanding of molecular structure in general.

The studies of magnetism and electricity were still main interests of Faraday, so he elaborated on Davy's pioneering work in electrochemistry. Davy had passed an electric current through a variety of molten metals and created new metals in the process. Faraday named this process electrolysis. He also bestowed names that were suggested by the British scholar Whewell and are still in use today: electrolyte, for the compound or solution that conducts electricity; electrode, for the metal rod inserted in the object; and anode and cathode for the positively and negatively charged electrodes, respectively.

In 1832, Faraday devised what became known as Faraday's laws of electrolysis, which hold that the mass of the substance liberated at an electrode during electrolysis is proportional to the amount of electricity going through the solution; and the mass liberated by a given amount of electricity is proportional to the atomic weight of the element liberated and inversely proportional to the "combining power" of the element liberated. The two laws showed there was a connection between electricity and chemistry. They also supported the suggestion that Franklin had made nearly 100 years earlier when he claimed electricity was composed of particles, a theory that would be another 50 years in the making.

In another experiment, Faraday sprinkled iron filings on a paper which was held over a magnet and noticed the filings had arranged themselves along what he called "lines of force." The connections along the lines showed where the strength of the field was equal. With the magnetic field now "visible," scientists began to wonder if space itself was filled with inter-acting fields of various types and this helped establish a new way of thinking about the universe. Up to this point most scientists had believed in the mechanical nature of the universe as established by Galileo and Isaac Newton.

Taking the concept of his lines of force one step farther, Faraday realized that when an electric current began to flow it caused lines of force to expand outward. When the current stopped, the lines collapsed. If the lines expanded and collapsed across an intervening wire, an electric current would be induced to flow through it, first forward then in reverse.

By now Faraday was giving public lectures, which were very popular, at the Royal Institute, just as Davy had. Faraday reasoned that if electricity could induce a magnetic field, then it should be possible for the reverse to be true. Taking an iron ring during one demonstration, Faraday wrapped half of it with a coil of wire that was attached to a battery and switch. André Ampère (1775–1836) had shown that electricity would set up a magnetic field in the coil. The other half of the ring was wrapped with a wire that led to a galvanometer. In theory, the first coil would set up a magnetic field that the second coil would intercept and convert back to electric current, which the galvanometer would register. Faraday threw the switch: the experiment worked. He had just invented the transformer. However, the result was not exactly what he expected. Instead of registering a continuous current, the galvanometer moved only when the circuit was opened or closed. Ampère had observed the same effect a decade earlier but ignored it because it did not fit his theories. Deciding to make the theory fit the observation, instead of the other way around, Faraday concluded that when the current was turned on or off, it caused magnetic "lines of force" from the first coil to expand or contract across the second coil, inducing a momentary flow of current in the second coil. Faraday had now discovered electrical induction. Meanwhile, in the United States, physicist Joseph Henry had independently made the same discovery.

In 1839, at the age of 48, Faraday had a nervous breakdown. Faraday never completely recovered. It is also possible that he was afflicted with a low-grade chemical poisoning. This was a common ailment that affected chemists at the time; Davy had suffered from it as well. In any event, Faraday's failing memory forced him to leave the laboratory.

Faraday published a book describing his lines of force in 1844, but because he lacked a formal education it was written without mathematical equations. Consequently the book was not taken seriously. When James Clerk Maxwell investigated the subject, he essentially came to the same conclusion as Faraday had, but used mathematics to prove his theory.

Although out of the laboratory, Faraday was by no means inactive. He investigated the effect of weak magnetic fields on nonmetallic substances and coined the words paramagnetic and diamagnetic to differentiate between the force of attraction and repulsion. Development of a theory to explain the two opposing forces, however, had to wait more than 50 years for the work of Paul Langevin. In the 1850s, during the Crimean War, the British government sought his opinion on the feasibility of using poisonous chemical weapons, and asked him to oversee their development. Faraday immediately said the project was very feasible, but he refused to have anything to do with its initiation.

Faraday died at Hampton Court, Middlesex, England. The word "farad," which is a unit of capacitance, was named in his honor.

See also Electricity and magnetism; Electromagnetic spectrum