In the Current Electricity section, you learned about electric charge, current, voltage and other related topics. But, just because you have a voltage does not mean electric current will flow. Electrons also need a complete loop of conductive material to flow, called a closed circuit . Let's look at a light switch. When you turn the switch "on", the switch creates a path that conducts electricity and electrons start to move—meaning electric current flows—and the light turns on. As soon as you turn the switch "off", the path is broken and electrons can no longer flow. The switch is like a drawbridge; switching it on is letting down the bridge so the electrons can cross (just like cars crossing a bridge) and provide energy to the light bulb. Illustration of how electric current can move through a closed loop of conductive material (left figure) but stops flowing whenever the loop is broken (right figure). This figure shows how a light bulb l...
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