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Learn about the history of our use of electricity as well as some very useful vocabulary including amber, atom, attract, battery, charge, conductor, current, electricity, electron, flow, frog, generator, Leyden, magnet, negative, neutral, neutron, positive, potential, proton, repel, scrap, shell, shock, spark, and static.
Without electricity you wouldn't be watching this video now. But what exactly is electricity? Electricity gets its name from amber. It gets its name from amber because amber was the first material to be shown to develop an electrical charge when rubbed with wool. The Greek for amber was elektron. Now, of course, when somebody first rubbed a piece of amber with a handful of wool they had no idea what electricity was. What they noticed, however, was that the amber they rubbed was suddenly able to attract anything light placed near it, like a scrap of paper or a feather. We now know that this force of attraction is produced by a build-up of electrons on the amber. All matter is made up of atoms. Atoms themselves have a nucleus made of neutrons and protons. Surrounding the nucleus are shells of electrons. There are normally just the right number of electrons to match the number of protons in each atom. Then we say that there is a neutral charge on the atom. Some atoms are very attached to their electrons and refuse to let them go. Other atoms lose their electrons more easily when they touch other atoms. Atoms that lose electrons are left with a positive charge. Other atoms steal electrons from other atoms that they come in contact with. Atoms that gain electrons are left with a negative charge. So when the piece of amber, which likes to steal electrons, comes into contact with a piece of wool, which easily loses electrons, electrons on the surface of the wool are captured on the surface of the amber. When the amber and the wool are separated, the wool becomes positively charged by losing electrons, and the amber becomes negatively charged by gaining electrons. A charge imbalance exists. It was an Englishman, William Gilbert, who, around 1570, started experimenting with amber. It was Gilbert who first used the term electrics for objects that attracted other objects after being rubbed. At this time, of course, neither Gilbert nor anybody else knew anything about atoms and electrons. In 1646, another Englishman, Sir Thomas Browne, wrote the Pseudodoxia Epidemica, or Enquiries into very many received tenets and commonly presumed truths. It was in this book that the terms electric and electricity first appeared. Electricity described the force of attraction caused by what we now know to be electrical charge. Neither Browne nor anybody else had any idea that the force of attraction was produced because atoms prefer to have a neutral charge. Nor did he realise that what he had called electricity was simply the flow of electrons from a negatively charged object to a positively charged object. By 1731, another Englishman by the name of Stephen Gray, did experiments to show that the electricity could flow over great distances. We still talk about the flow of electricity as if it were a fluid like water. Gray also found that metal conducted electricity better than other materials. Since then, things that conduct electricity well are called conductors and those that don’t, like amber, are called nonconductors. Gray realised that because amber was a non-conductor, the electricity generated on it when it was rubbed with wool could not go anywhere. As soon as a conductor, such as metal, touched a nonconductor like amber, the electricity was instantly conducted away and that was what produced the electric shock and even the bright spark that was often seen. The news of Gray's experiments spread as quickly as the flow of electricity through his conductors. By 1733, they had come to the attention of a Frenchman named Charles Francis Du Fay. Du Fay did some experiments with electrified corks hanging on strings and discovered that there were two kinds of electric fluid. Corks with the same kind of fluid in them repelled each other, while those with different kinds attracted each other. By 1745, people were putting the fluid in special glass jars. The bottom of these glass jars had a thin coating of metal on the inside and the outside. They had a cork at the top into which was inserted a brass rod with a chain at the end. This brass chain touched the metal coating at the bottom of the jar. If the top of the brass rod was touched by a piece of charged material, such as glass which had been rubbed with a piece of silk, the electricity flowed into the jar. The electricity could not escape from the jar because the cork at the top and the glass of the jar were non-conductors. The more times the brass rod was touched with a charged glass rod, the more electricity became stored inside. A professor at the University of Leyden in the Netherlands did experiments with this type of jar and it became known as a Leyden jar. Peter van Musshenbroek, the professor, discovered just how much electricity he could store in the jar when he was knocked off his feet by a powerful shock and had to spend two days in bed. In 1747, Benjamin Franklin received a Leyden jar from England and set about doing some of his own experiments. He soon concluded that electricity flowed because objects had different types of electric charge. Objects that had too little charge would repel other objects that also had too little. Such objects need more charge to reach a neutral charge and do not want to give away any charge that they have. Objects that have too much charge also repel each other. They do so because both objects with too much charge need to lose some charge to reach a neutral charge. Put an object with too much charge together with an object with too little charge, however, and they attract each other. They attract each other because they want to neutralise the positive and negative charges and attain a neutral charge. Unfortunately, Franklin had no way of knowing which charge was negative and which was positive. He guessed and he guessed wrongly. It didn’t affect his theory, but it did mean that schoolchildren have been left thoroughly confused ever since. It is counter-intuitive to say that an object with a negative charge has too many electrons while an object with a positive charge has too few. But it’s too late to change now. Despite being super-intelligent, Franklin decided to fly a kite during a thunderstorm. He wanted to know if lightning was the same thing as the electricity in his Leyden jar. Franklin survived to make the first practical use of centuries of electricity experiments when he invented the lightning conductor in 1753. In 1771, an Italian biologist, Luigi Galvani, was playing with his own Leyden jar. He was shocked to discover that he could make a dead frog’s leg twitch with the electricity. Living things, he deduced, worked through some kind of electricity. Galvani’s nephew, Giovanni Aldini, continued his uncle’s experiments. Aldini went to Newgate in London on the 18th January 1803, and made the legs, face and right hand of George Foster twitch using electricity. A witness, Mr Pass, the beadle of the Surgeon’s Company, was so horrified by what he saw that he died of fright on his return home. This was not entirely surprising as the twitching George Foster was himself dead, having been hanged for the drowning of his wife and child in the Paddington Canal. Aldini’s shocking experiment inspired Mary Shelly to write her famous novel, Frankenstein; or The Modern Prometheus1 . Another Italian, Allessandro Volta, wanted to do more than make the legs of the dead twitch. After some experiments where he attached frog’s legs to metal hooks in a thunder storm, Volta discovered that it was not the muscles of frogs and criminals that created electricity, but rather a chemical change in different types of metal. You see, while the frogs legs twitched on the metal hooks when there was thunder in the air, they also twitched on the hooks when the sky was clear. Volta realised that it was not the electricity in the air that was causing the twitching, but rather the reaction of the fluids in the frog’s legs with the metal of the hooks they were impaled on. This reaction was producing an electrical current. You can experience the same effect if you have a metal filling in your tooth. Take a piece of silver foil and bite down on it and let the foil and filling come in contact with each other. The saliva between the foil and the metal of the filling will begin generating electricity which will feel rather unpleasant as it courses up the nerves of your tooth. 1 Check the resources link in the activation pack for the Frankenstein lesson. In 1800, Frogs throughout Italy breathed a sigh of relief as Volta turned his attentions to strips of copper and tin and bowls of salty water. He set up a battery of such bowls and produced electricity. Volta had invented the battery. Unlike the electricity produced in bars of amber or glass, Volta’s electricity flowed through the wires for as long as the chemical changes were taking place in the metals. Keep biting down on the foil, if you can bear it, and you’ll see what I mean. Volta’s moving electricity is called an electrical current because it flows. Electricity in glass and amber doesn’t move and is called static electricity. Something that is static is not moving. Because Volta’s electrical current moved, people saw potential in batteries and began experimenting. Batteries improved quickly and an Englishman by the name of William Nicholson used the electrical current to split water into hydrogen and oxygen in 1800. By 1819, the Danish scientist, Hans Christian Oersted, had found a connection between electricity and magnetism. He showed that electricity could produce a magnetic field as it flowed through wires, and the electromagnet was soon invented. Michael Faraday, another Englishman, then realised that if electricity could produce a magnetic field, then a magnetic field could produce electricity. In 1831, he attached a copper plate to a steam engine which turned the plate around and around in a magnetic field. A current of electricity was generated and the electricity generator was born. The new and reliable source of electricity enabled the invention of the telegraph in 1844, the electric light in 1879, and very shortly afterwards the electricity bill. Today, we plug our plugs into our household sockets and power our numerous domestic appliances without giving electricity a second thought. We switch on the lights, godlike, whenever we need to let there be light. And we often forget to switch them back off again, thus negating the power-saving intent of our expensive fluorescent energy-saving light bulbs2 . The only time we realise just how important electricity is to our lives is when we are suffering a power cut or blackout. Only then do we really appreciate just how much we depend on electricity in our modern world. The harnessing of electricity is undoubtedly the most important development in the history of mankind. After tens of thousands of years of rather pedestrian technological development, electricity has enabled us to plumb the depths of the world’s oceans and begin to explore the universe beyond the tight confines of our world. It also enables me, as an English teacher, to give classes to students around the world, as if I were sitting alongside them in their own homes and offices. On the other hand, it has also given us television, the mobile phone and a terror more terrifying than Frankenstein’s monster - the electricity bill. So, perhaps it’s a mixed blessing, after all. Even so, I feel that we owe a lot to all of the people mentioned in this video, as well as to the many others who I didn’t have room to include.
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