Electricity generation - chemical process:
An esteemed Italian physicist, Count Alessandro Giuseppe Antonio Anastasio Volta, developed the first chemical battery to produce an electric current. In 1800 he showed that an electric current could be made to flow by connecting a wire conductor between two strips of metal standing in a container of fluid.
Volta used a strip of copper and a strip of zinc in a solution of sulphuric acid and so produced the first electric battery, or voltaic cell (See figure below).
Above - An illustration demonstrating that by placing a copper and zinc rod in a solution of dilute sulphuric acid generates a small charge of electricity. This is known as a wet cell battery.
Previously electricity had only been thought of in terms of intermittent sparks and surges such as that in static electricity (caused by friction and lightning). Volta's invention provided a continuous electricity source for early telephone and telegraph systems. He showed for the first time that an unbroken flow of electricity could be maintained.
In the voltaic cell, the copper strip or rod is called a “positive electrode” and the zinc rod a “negative electrode”. The acid fluid is called an “electrolyte”. This enables the chemical reaction to take place. Modern “dry cell” batteries have a chemical paste instead of a liquid electrolyte. (Torch batteries and transistor radio batteries are examples of “dry cells”.)
When the battery is connected to an electrical circuit, there is a flow of electrons (an electric current). Electrons flow from the negative rod of the battery (electrode) to the positive one through the connecting wire conductor. The circuit must be complete (unbroken) for a current to flow. (See figure below)
Above - flick the switch to open or close the circuit.
Source: Western Power’s World of Energy.
Electron flow through a conductor is similar in many ways to the flow of water through a pipe. In both cases a difference in pressure between the ends of the circuit is used to cause the flow, and in both cases the greater the pressure difference or the larger the conductor or pipe, the greater the flow.
The force of pressure of electricity today is measured in volts – named after Count Alessandro Volta. For example a typical modern torch would use two or more dry cells rated at 1.5 volts each. (While cells are commonly called batteries, strictly speaking a battery consists of two or more cells linked together).
For more information about Count Volta and the world’s first battery, go to:
 http://inventors.about.com/library/inventors/bl_Alessandro_Volta.htm
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