9.1 Introduction to Batteries
Batteries create electricity using chemical reactions between liquid or solid chemicals and different types of metals to move electrons along a wire. All batteries for common household use have a + and a – sign on them. The positive and negative ends of the battery represent the two electrodes of the battery. Electrodes are two different kinds of metals that can move electrons between them, which creates electricity. The electrode that electrons move away from (with a negative sign) is called an anode. The electrode that electrons move towards (with a positive sign) is called a cathode.
Batteries only produce an electrical current when you attach them to something that runs on electricity. They can stay in a drawer or on a shelf for years without producing electricity, but as soon as they’re connected to a toy or an appliance that uses electricity, batteries start using the chemical energy inside them to make an electric current.
When a battery is connected to a motor or other device that is powered by electricity, ions start moving from the cathode to the anode through the material that separates them, called the electrolyte. Electrons don’t travel through the electrolyte, so they have to move through the wires connected to the motor, which creates an electric current.