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Q:
I would like to know how a battery works, and why it works in that way?
- sissela
Helsingborg, Skania, Sweden
A:
Most batteries have two electrodes made of different materials, with some sort of chemical solution or paste in between. When the battery is used, chemicals near 1 electrode start to do a reaction that produces extra electrons. The electrons flow (flowing electrons are called current) through a circuit into the other electrode, where they are taken up in another chemical reaction. On the way through the circuit the current drives a radio or whatever you have the battery run.
The chemical reactions at the two electrodes always have to be different. Otherwise, there would be no reason for the electrons to push from one side to the other. The chemicals have to start in a high energy (more precisely, high free energy) state, so that in falling down to the lower energy state they can supply energy to the circuit. As the battery is used, the chemicals inside are used up, leaving some lower-energy forms. Eventually, the high-energy forms get used up and the battery is "dead".
Different types of batteries use different chemicals. Car batteries use lead and sulfuric acid. Cell phones and laptop computers use nickel and cadmium. The normal batteries you see in a store use alkaline manganese dioxide.
Adam (& Mike W.)
(published on 10/22/2007)
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