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  #1  
Old 01-21-2006, 01:04 PM
JSL1996 JSL1996 is offline
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Default why do you need a postive and negative side of a battery

I am in 4th grade and I have to do a project for science fair, I want to make a battery, but I needed a question that I could answer, and my question was why do you need a postive and negative side on a battery.
please can anyone help me with this question
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  #2  
Old 02-23-2006, 07:31 PM
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Caboose38924 Caboose38924 is offline
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Thumbs up Battery Project

Hi.
First of all, you need a postive and negative side, to complete the circuit to continue the flow of energy wherever the energy is going. Instead of building a battery, how about making a human one? Here is the project. Good Luck!

A Human Battery
In a nutshell, a battery (a device that produces electricity by means of chemical action. A battery consists of one or more units called electric cells. Each cell has all the chemicals and parts needed to produce an electric current.) uses a chemical reaction to produce an electrical current (the movement or flow of electric charges). In this experiment, we will create an electric current using nothing more than our own bodies (Reeko promises this won't hurt.... much).

Mount the copper and aluminum metal plates to two separate pieces of wood.
Connect one plate to one of the DC microammeter's terminals using an alligator clip and the hookup wire. Connect the other plate to the second terminal. A DC microammeter, which is an instrument that measures the electric current in a circuit (is the path followed by an electric current- electricity must flow in a circuit to do useful work), can be purchased from your local Radio Shack store.
Now place one hand on each plate.
You should see an electric current generated on the meter. If you don't see a reading then simply reverse the connections. If you still don't see a reading then you may need to clean the metal plates (or get a pair of better reading glasses).

When you place your hands on the metal plates, a thin film of sweat on your hands acts just like the acid in a battery, producing a chemical reaction with the copper plate and a chemical reaction with the aluminum plate. Your hand actually takes negatively charged electrons (a negatively charged subatomic particle) away from the copper plate (leaving positive charges behind) and gives electrons to the aluminum plate (causing it to become negatively charged). This difference in charges produces an electrical current which flows through the meter.

Wet both hands.
Once again, place one hand on each plate.
Metals are very efficient at this electrical current we have created. Your body resists the flow of current (through the skin). When you wet your hands you greatly decrease the resistance and thus increase the current giving you a higher reading on the meter.

Parent's Note. Batterys have actually been around a lot longer than you'd think. The first practical battery was probably developed by Count Alessandro Volta, an Italian scientist, in the late 1790's. Volta's invention became known as a voltaic pile. It consisted of a stack of pairs of silver and zinc disks. The pairs were separated from one another by disks of cardboard moistened with a salt solution.

In 1836, John F. Daniell, an English chemist, introduced a more efficient primary cell. The Daniell cell had two liquid electrolytes and produced a steadier current than Volta's device. In 1859, the French physicist Gaston Plante invented the first secondary battery (a battery that can be recharged), the lead-acid storage battery. During the 1860's, another French scientist, Georges Leclanche, invented a type of primary cell from which the modern dry cell was developed.

Through the years, scientists have designed smaller but increasingly powerful batteries for the growing number of portable electric devices. For example, a lithium cell is so tiny that it is often called a button battery. But it produces voltages (differences in potential (or electrical state) related to the electrical forces that 'push' charges through a conductor) higher than any other single cell. It uses lithium metal as the negative electrode and any one of several oxidizing (oxidize means to combine with oxygen) agents as the positive electrode. Lithium cells are used mainly in calculators, cameras, pacemakers, and watches.
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Old 04-05-2006, 02:19 PM
yasmire whigham yasmire whigham is offline
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Post why you need a positive and negative side of batteries

The reason why you need a positive and negative side of a battery is probably because when you buy something that needs batteries,each side might need a certain amount of energy.For example,if you buy a CD player,and you open up a compartment that needs batteries,it has two slots.One side has a - sign,and one side has a + sign.There might have to be a certain amount or certain type of energy.
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Old 11-07-2008, 02:42 PM
starlightgirl starlightgirl is offline
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Default batteries

during a sceince project i believe i discoverd one reason:

after the electrons have flowed through the lightbulb they go back through the wire into the positive side which contains a positively charged carbon rod that reacts with the granulated maganese dioxide and granulated carbon to neutralize the electrons.
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