The 'Shocking' Story of the Battery
- Monday, March 08, 2010
What do automobiles, computers, flashlights, and radios all have in common? If you think about it, you'll realize that each one of these things has a battery somewhere inside it. Batteries are devices that store electricity so that we can use it when we want to. Some types of batteries are designed to be used once. When they go "dead," we throw them away. Others are able to be "recharged" and used over and over. As it turns out, it took a long time for people to figure out enough about electricity to be able to invent the battery. It was a fascinating journey that led to an invention that changed the world.
The World Before the Battery
Most people in the United States have heard that Benjamin Franklin discovered electricity one day while flying a kite in a thunderstorm. The truth of the matter is that it was not Benjamin Franklin. No one knows exactly who discovered electricity, but the earliest mention of it is from an observation made by a Greek philosopher named Thales about 600 B.C. Thales noticed that when he rubbed a piece of amber with a wool cloth, small bits of straw seemed to jump and stick to the amber. Although he did not know exactly what was happening, he had discovered static electricity.
Thales' experiment was repeated many times over a period of centuries, but nothing useful ever came from it. Scientists were naturally curious, but they never devised any experiments to investigate this strange phenomenon further. In the mid-1700s, an English physicist named John Canton invented a device called a pith ball electroscope. The device held two small balls by silk threads. When he rubbed a piece of glass with a cloth and moved it toward the ends of the silk threads, the two pith balls moved apart. This was the start of understanding electricity. Something was causing the pith balls to repel one another, but what?
Also in the mid-1700s, a Dutch scientist named Pieter van Musschenbroek invented a device at the University of Leyden which became known as a "Leyden Jar." It was a glass jar that could store electricity! Actually, it was a very special glass jar. The inside was coated with a metal foil. The outside had a second metal foil wrapped around it. By rubbing a piece of glass with cloth, van Musschenbroek could continue to add static electrical charge to this special jar.
What van Mussechenbroek had really invented is an electrical component called a "capacitor." Now scientists could at least store electricity for use in experiments. The problem was, this was static electricity. When someone went to use it, the electricity would "spark" and quickly go away. Have you ever given someone an electrical shock when you touched them? You were storing static electricity in your body. In a way, you were a Leyden Jar! In order for scientists to better understand electricity, they needed a way to store it and control it for their own uses.
Italian scientists made some observations that would help accomplish this task. Believe it or not, the invention of the battery began with an observation made in the late 1700s by Luigi Galvani, a professor of anatomy at Bologna University in Italy. Galvani was studying frogs to try to learn how nerves make muscles move. In order to do this, he had to dissect frogs. One day, when he had freshly killed a frog, a nearby lightning strike caused the frog's leg to move violently. Later, Galvani observed that when he hung a frog's leg on a brass hook, and the hook touched a different kind of metal, the frog's leg would twitch. His conclusion was that he had discovered "animal electricity."
In 1800 at the University of Pavia, also in Italy, a physics professor named Alessandro Volta heard about Galvani's discovery. After studying what Galvani had done, Volta concluded that the electricity was not in the frog, but in the metals. He created a unique experiment to prove this. Volta took some silver disks, some zinc disks, and some pieces of cloth that he had soaked in salt water. He built a stack with a silver disk, a piece of wet cloth, a zinc disk, and another piece of wet cloth. He repeated the sequence to make what was called a "Voltaic Pile." This voltaic pile created a chemical reaction that caused electricity to flow. Volta had built the first battery!
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