In this topic you will learn how electricity moves from one place to another.

A complete path that electricity can move through is called a circuit. A circuit is a system made of many parts that work together to allow electricity to flow. The electricity that flows through a circuit is a little different from static electricity. Remember: static electricity is a buildup of electric charge. The electricity that flows through a circuit is called current electricity. Current electricity is a moving electric charge.

In many ways, current electricity behaves like flowing water. Both flow only if they have a clear path. With electric circuits, a complete path is called a closed circuit. In a closed circuit, there are no gaps or places where current cannot flow.

An incomplete path is called an open circuit. No current flows in an open circuit. The path is not complete. There are gaps. As in any system, when a part is missing, the system does not work properly. A switch is a device that can open or close a circuit. It is used to control current in a circuit.

A light bulb is a ball of glass. Inside the bulb most of the air has been removed. The bulb has a metal base. Two wires extend from the base into the bulb. These wires are good conductors. Between the two wires is a thin, coiled wire. It is called a filament. The filament is a poor conductor. It is a resistor. A resistor is a material through which electricity has difficulty flowing. This resistance causes the filament to get hot and glow, to produce light and heat.

Current always follows the path of least resistance. Current will flow through a conductor rather than a resistor. When too much current flows through a conductor, a short circuit is made. In your home a short circuit can occur if frayed or broken wires touch.

Electricity is an important part of our lives. Understanding how electricity travels helps us to know what parts of a circuit to examine when electricity doesn't flow.