Alessandro Volta

Born: February 18th, 1745, Como, Italy
Died: March 5th, 1827, Como, Italy

In 1800, as the result of a professional disagreement over the galvanic response advocated by Luigi Galvani, Volta developed the so-called voltaic pile, a forerunner of the electric battery, which produced a steady electric current. Volta had discovered that using moisture between two different metals, electricity is created.

Volta had determined that the most effective pair of dissimilar metals to produce electricity was zinc and silver. Initially he experimented with individual cells in series, each cell being a wine goblet filled with brine into which the two dissimilar electrodes were dipped.

In this way, a new kind of electricity was discovered, electricity that flowed steadily like a current of water instead of discharging itself in a single spark or shock.

Volta showed that electricity could be made to travel from one place to another by wire, thereby making an important contribution to the science of electricity.

The unit of electrical potential, the Volt, is named after him.

Jean-Marie Ampere

Born: 20th January 1775, Lyon, France
Died: 10th June 1836, Marseille, France

Andre Marie Ampere, a French mathematician who devoted himself to the study of electricity and magnetism, was the first to explain the electro-dynamic theory. A permanent memorial to Ampere is the use of his name for the unit of electric current.

It is on the service that he rendered to science in establishing the relations between electricity and magnetism, and in developing the science of electromagnetism, or, as he called it, electrodynamics, that Ampère’s fame mainly rests.

On September 11, 1820 he heard of Ørsted’s discovery that a magnetic needle is acted on by a voltaic current. On the September 18 he presented a paper to the Academy, containing a far more complete exposition of Ørsted’s discovery.

The whole field thus opened up he explored with characteristic industry and care, and developed a mathematical theory which not only explained the electromagnetic phenomena already observed but also predicted many new ones.

In recognition of his work in this field the term for the measurement of electric current was coined after his name.

Georg Simon Ohm

Born: March 16th, 1789, Erlangen, Germany
Died: July 6th, 1854, Munich, Germany

Ohm, A German mathematician and physicist, was a college teacher in Cologne when in 1827 he published, “The Galvanic Circuit Investigated Mathematically”.

His theories were coldly received by German scientists, but his research was recognized in Britain and he was awarded the Copley Medal in 1841.

Ohm’s name has been incorporated in the terminology of electrical science in Ohm’s Law, the proportionality of current and voltage in a resistor, and adopted as the SI unit of resistance, the ohm (symbol Ω).

Michael Faraday

Born: September 22nd, 1791, Newington Butts
Died: August 25th, 1867, Hampton Court Palace, Molesey

The generation of an electrical current on a practical scale goes to the English born and self-educated, Michael Faraday.

His interest in electromagnetism, discovered by Danish scientist, Hans Christian Ørsted, enthused him enough to take earlier experiments even further. The question he asked was, if electricity could produce magnetism, could the reverse also be true?

In 1831, he began his great series of experiments in which he discovered electromagnetic induction. He found that if he moved a magnet through a loop of wire, an electric current passed through the wire. His demonstrations exposed the concept that electric current produced magnetism.

Faraday then used the principle to construct the electric dynamo, the ancestor of modern power generators.

Nearly 40 years went by before a really practical DC (Direct Current) generator was built by Thomas Edison.

In 1878 Joseph Swan, a British scientist, invented the incandescent filament lamp and within twelve months Edison made a similar discovery in America.

Joseph Swan

Born: October 31st, 1828, Bishopwearmouth, Sunderland
Died: May 27th, 1914, Warlingham

Thomas Edison

Born: February 11th, 1847, Milan, Ohio, USA
Died: October 18th, 1931, West Orange, New Jersey, USA

Swan and Edison later set up a joint company to produce the first practical filament lamp. Prior to this, electric lighting had been crude arc lamps. Edison used his DC generator to provide electricity to light his laboratory and later to illuminate the first New York street to be lit by electric lamps, in September 1882.

Edison’s successes were not without controversy, however although he was convinced of the merits of DC for generating electricity, other scientists in Europe and America recognized that DC brought major disadvantages.

George Westinghouse

Born: October 6, 1846 Central Bridge, New York
Died: March 12, 1914 New York City

Nikola Tesla

Born: July 10, 1856, Smiljan, Croatia
Died: January 7, 1943, Manhattan, New York City, New York, United States

Westinghouse was a businessman who had become very interested in electrical power distribution. When he looked at Edison’s scheme, he decided that it was far too inefficient for the large sizes he hoped to produce.

Edison’s power network was based on low-voltage DC, which meant large currents and serious power losses. Several European inventors were working on “alternating current (AC)” power distribution. An AC power system allowed voltages to be “stepped up” by a transformer for distribution, reducing power losses, and then “stepped down” by a transformer for intended use.

A power transformer developed by Lucien Gaulard of France and John Gibbs of England was demonstrated in London in 1881, and attracted the interest of Westinghouse. Transformers were nothing new, but the Gaulard-Gibbs design was one of the first that could handle large amounts of power and promised to be easy to manufacture. In 1885, Westinghouse imported a number of Gaulard-Gibbs transformers and a Siemens AC generator to begin experimenting with AC networks in Pittsburgh.

An AC motor was a more difficult task, but fortunately a design was already available, at least in principle. The brilliant Serbian inventor Nikola Tesla had already dreamed up the basic principles of a polyphase electric motor.

As luck would have it, he had come to the United States while in the employ of the Edison Company. Tesla and Edison didn’t get along well, one reason being that Tesla was interested in AC systems, and quickly parted company.

Westinghouse got in touch with Tesla, and obtained patent rights to Tesla’s AC motor.

Tesla hadn’t actually built a working motor at that time, but Westinghouse hired him as a consultant for a year and helped turn his polyphase AC motor into a reality.

The work carried out by Tesla and Westinghouse led to the standard modern US power-distribution scheme:
Three-phase AC at 60 Hz (In the UK we use 50Hz).

This was chosen as a rate high enough to minimize light flickering, but low enough to reduce reactive losses.