Who the hell are we? And what are we doing here?

Part 70 - Electricity

Our remote ancestors knew about shocks from electric fish. Egyptians from 2750 BCE referred to them as "Thunders of the Nile." The Greeks and Romans also reported the numbing effect of electric shocks delivered by electric catfish and knew that such shocks could travel along conducting objects. The Arabs described the electric ray using the Arabic word for lightning.

Around 600 BCE, Thales of Miletus created static electricity by rubbing rods of amber with cat's fur to attract light objects like feathers. He believed that friction made amber magnetic in contrast to minerals such as magnetite, which needed no rubbing.

In 1600, William Gilbert (Queen Elizabeth's physician) carefully studied electricity and magnetism. He wrote De Magnete, coined the word electricus (from elektron, the Greek word for "amber") which first appearance in print as 'electric' in Thomas Browne's Pseudodoxia Epidemica of 1646.

In the 17th and early 18th centuries Otto von Guericke built a friction machine to generate electricity continuously; Stephen Gray identified conductors and non conductors and C. F. du Fay showed the difference between positive and negative electricity.

The Leyden Jar was invented by Ewald Georg von Kleist and Pieter van Musschenbroek around 1746 as a way to temporarily store a high-voltage electric charge. It was the first condenser or capacitor and was used for many early experiments in electricity and electrostatics.

Benjamin Franklin's research was documented by Joseph Priestley in 1767 in his History and Present Status of Electricity. In 1752 Franklin was said to have flown a kite in a storm creating a succession of sparks from a key to the back of his hand and demonstrating that lightning was indeed electrical in nature. This led to the invention of the lightening conductor to protect buildings from lightening strikes.

John Canton invented an instrument to measure electricity that was standardized by Alessandro Volta and in 1787 improved by Bennet as the gold leaf electroscope.

In 1791, Michael Faraday discovered the principles of electromagnetic induction, diamagnetism and electrolysis. In 1821, he discovered that a wire carrying an electric current rotated around a fixed magnet and also demonstrated a that a magnet, rotated around a conducting wire circuit, produced a current in the circuit. In 1831, he built the first electric motor and also the first electrical generator. (Also known as a dynamo). He also demonstrated that the voltage of an alternating current could easily be changed by placing two coils of wire together; the voltage in one coil would create a voltage in the other in direct relationship to the number of windings in each coil. (This device is now known as an electrical transformer). The unit of capacitance, the farad,is named in his honour.

In March 1861, James Clerk Maxwell took the work of Faraday and others and summarized it in a set of equations which is accepted as the basis of all modern theories of electromagnetic phenomena.