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Q & A: Reversable Batteries?

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Most recent answer: 10/22/2007
just wondering. why do batteries have a positive and negative side? does it really matter which way the electrons flow? and why is there a bump on the positive side and why is it flat on the flat side? thanks.
- J (age 14)
I'll take your question one step at a time. First of all, there is a big difference between the positive and negtative side of a bettery. Inside the battery, there is a chemical reaction that sends out electrons from the negative side and other electrons will flow into the positive side.

It is also important which way the electrons flow, for many devices. Some things would work with the batteries backwards, but most wouldn't. For example, I was working on a project and accidently put in something backwards, it actually heated up very very hot and could have caught something on fire. Probably that's because some electronic component (maybe a diode) let current flow very easily one way but not the other. So it is very important to always put batteries in correctly. For some simple devices (like an ordinary flashlight) it doesn't matter at all which way the current goes.

As for the bump on the positive side, this doesn't make a difference as to how the electronics work. The bump is there to help us. If everyone knows that the bump means positive, then there is less of a chance of putting the battery in the wrong direction.


(published on 10/22/2007)

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