Storing Electric Energy> What do you get when you cross zinc and silver? “Zinc and silver” is one dumb answer. Here’s a smarter one: electricity! Two different metals, side-by-side, can create an electric charge.
That’s how batteries get their volts. The first battery, built in 1800, had a stack of zinc and silver disks. In between the metal disks were paper disks soaked in saltwater. The two metals created charges. The saltwater conducted (carried) the charges through the stack.
Batteries may use lead, copper, carbon, or other substances in place of zinc and silver. And many different chemicals take the place of saltwater. In time, the available charges in the metals or the chemicals are used up. Then the batteries “die,” or can’t make current flow anymore.
To make a battery’s charges flow, just give them a path to follow. In the zinc and silver battery, simply link the top disk and the bottom disk with a wire. The current flows out the battery, along the wire, and then back in the battery. This loop is called a circuit.
On modern batteries, look for a plus (+) sign and a minus (-) sign. The current enters the battery near the plus sign. It exits the battery near the minus sign. Link the plus part and the minus part with a wire to make a circuit. Link the plus and the minus to a light bulb and . . . bing! The current makes the light bulb light.
