Although it is possible to trace the history of the harnessing of electrical power and identify the people responsible for various breakthroughs along the way, it is difficult to put a name to the person who first discovered electricity. Very early in human history, people would have witnessed lightning, an obvious natural manifestation, but would have been unable to explain it. The known history of electricity goes back to at least 620-550 BCE, when, in ancient Greece, it was found that rubbing fur on amber caused an attraction between the two. This discovery is credited to the philosopher Thales of Miletus. It was to be many centuries before anyone was able to connect this phenomenon with lightning, and a century more before electrical currents were put to practical use.
By the 17th century, many electricity-related discoveries had been made, such as the invention of an early electrostatic generator, the differentiation between positive and negative charges, and the classification of materials as conductors or insulators. In the year 1600, English physician William Gilbert first made the connection between the attraction of oppositely charged objects and magnetism. He coined the term electric, from the Greek elektron — meaning amber — to identify the force that certain substances exert when rubbed against each other.
Benjamin Franklin is perhaps the name most associated with electricity. In 1750, he sought to prove that lightning was caused by electricity by describing an experiment in which an electrical conductor would be used to extract power from a thundercloud. It seems that before he was able to carry this out, a French experimenter named Thomas-Francois Dalibard, who had read Fraklin’s writings on the subject, successfully obtained an electrical discharge from a thundercloud using a 40 foot (12.2 meter) metal pole in May 1752. Franklin is credited with carrying out a similar experiment in June of that year, in which he flew a kite with a metal key attached to it into a suitable cloud. The precise historical details are unclear, but he may have then retrieved the key and discharged electricity from it.
While it is not clear exactly when, how, or even if, Franklin actually carried out his lightning experiment, he is rightly credited with the idea behind it. The relationship between lighting and electricity having been confirmed, he went on to invent the lightning rod, a metal pole that safely conducts electricity away from a building during a thunderstorm. Franklin observed and documented other electrical phenomena, but it was left to others to determine the true nature of electricity and harness its power.
Galvani, Volta and the Invention of the Battery
The Italian scientists Luigi Galvani and Alessandro Volta both played a role in the development of the first battery in the late 18th and early 19th centuries. In 1780, Galvani discovered what he called “animal electricity” when he found that a frog’s leg would contract if connected to two different metals. Volta later demonstrated that the “animal” part was unnecessary, and that pairs of different metals, such as zinc and copper, could produce a current if immersed in an electrolyte, such as salt water. This device is known as a galvanic cell.
Volta went on to create a “voltaic pile” consisting of alternate layers of copper and zinc separated by paper soaked in salt water. This generated a larger current and is credited as the first battery. These devices work because zinc has a greater tendency to lose electrons than the copper, so that when they are connected by an electrolyte, electrons will flow from one to the other, forming a galvanic cell. A series of galvanic cells connected together, as in a voltaic pile, makes up a battery.
It has been theorized that an artifact discovered in Iraq, and thought to date from sometime between 224 and 640 CE, might have been a type of battery. It consisted of small terracotta pot containing a copper tube surrounding an iron rod. If filled with an electrolyte, such as grape juice, it can produce an electric current. Most scientists, however, think that the pots were used for storing scrolls and that their ability to generate a current is purely coincidental.
In 1831, the English scientist Michael Faraday discovered that an electrical current could be induced in a copper wire by a moving magnetic field. This led to two crucial inventions: the dynamo and the electric motor. A dynamo generates an electrical current by the relative motion of coils of copper wire and magnets and is the primary method employed today to generate electricity for domestic and industrial use. The electric motor exploits the same principle: a current flowing in a magnetic field produces movement.
Thomas Edison and Nicola Tesla
Following the invention in 1860 of the electric light bulb by the British physicist Joseph Swan, the American inventor Thomas Edison had the idea, in the late 1800s, of transmitting electricity via cables to every home to provide lighting. Edison planned to use the direct current (DC) produced by the generators available at the time. This, however, would have meant placing generators at frequent intervals, as a lot of power was lost through the resistance of the cables.
Nicola Tesla, a Serbian-born engineer and inventor who worked with Edison for a time, developed a new kind of generator that produced a current that switched direction many times a second, known as alternating current (AC). This had the advantage that the voltage and current could be varied using a transformer. Power loss could be minimized by transmitting the electricity at low current and high voltage, then reducing the voltage and increasing the current for domestic use. Despite fierce opposition from Edison, AC was adopted, and this is the kind of current that is used in homes today.