Complete circuit: from amber to ice

In 1600 British scientist William Gilbert coined the term electricus, from the Greek word for amber, and from which we get the words electric and electricity. He was fascinated by the ancient Greeks discovery that if you rubbed a piece of amber (fossilised tree resin) with a bit of fur, the amber was able to attract small objects. How and why the Greeks first decided to do this type of rubbing remains a mystery but they had discovered the power of static electricity.

A build-up of electrical charge through rubbing forms the core mechanism of the famous Van de Graaff generator much beloved in school physics labs. Invented in 1929 by American physicists Robert Van de Graff the original device used a silk ribbon bought at a local store. The ribbon acts as a fast moving belt, running between two rollers. Friction between belt and rollers allows the buildup of electrical charge in the metal dome on top of the machine where a metal comb strips off the charge. Massive Van de Graaff generators are used to explore the structure of matter by creating high energy ion beams and massive voltages.

Voltage is named after Italian physicist Alessandro Giuseppe Antonio Anastasio Gerolamo Umberto Volta. He invented the first battery in the 1800s comprising zinc, copper and a jar of sulphuric acid. The battery wasn’t particularly good, it ran down very quickly, and the sulphuric acid made it rather dangerous, but for his hard work he was made a count by Napoleon in 1801.

Biobatteries produce electricity using tricks from nature. A prototype biobattery using waste paper was demonstrated in 2011. In this battery shredded paper or old cardboard is dropped into a tank containing water and special enzymes. The enzyme, cellulase, decomposes the papers into glucose sugar which is then combined with oxygen and further enzymes to produce electrons and hydrogen ions.

Biobatteries can be made using fruit too. If you take a citrus fruit like a lemon, lime, orange or grapefruit, and puncture it with a copper nail and a zinc nail a small voltage can be generated. It follows the same chemical principals as Volta’s original sulphuric acid filled battery. A fruit juice (citric acid) based battery has been used to power a walkman music player.

Electricity can be generated by people walking. In areas where lots of people walk test devices have been installed that convert the pressure of peoples foot fall into electricity, for example to power advertisement boards or lights. These devices replace standard paving stones or carpet tiles, and are being tested in the corridors of one school in England.

Substances that create an electrical change when they are put under pressure are called piezoelectric, these include bone, and the naturally occurring crystal quartz, which scientist William Gilbert mistakenly believed was an especially hard form of water, formed from ice.