(Lansing State Journal, February 3, 1993)
Question submitted by Katie Yurgelaitis.
There are two types of battery, the dry cell (like those used in flashlights) and a wet cell (used in automobiles). Inside a dry cell battery is a chemical paste called the electrolyte that can conduct electricity. The electrolyte is made up of billions of billions of positive and negatively charged particles. The battery is housed in a case that is made of zinc and running through the center of the zinc case is a carbon rod. Electrolyte fills the space between the zinc case and the carbon rod. The rod and the case acts as electrodes. Chemical reactions in the electrolyte send positive particles to the carbon electrode and negative particles to the zinc. The electrodes are fitted with contact points which allow the battery to be connected to a circuit. When the electrodes are connected in this way, the charges that have built up on the electrodes are free to move. They flow from one electrode to the other, thus, flowing through the circuit. This flow of charge is what we know as electric current. When the electrolyte cannot produce a charge flow any more the battery is "dead".
You can make your own battery at home by using a lemon. Push two pieces of metal into the lemon. These two pieces have to be different kinds of metal (such as a brass thumbtack and a steel paperclip). Make sure that the two metals do not touch one another! Wrap some copper wire around the ends of the metals and connect the other ends of the wire to a flashlight bulb. The light bulb should light up. The acid in the lemon acts as the electrolyte which lets particles move to the electrodes which are the thumbtack and the paperclip. The electricity then flows through the lightbulb until the electrolyte (acid) around the metal pieces is no longer able to react.