How Can I Understand the Basics of Electricity?

Imagine yourself standing with a garden hose, ready to soak some unsuspecting passerby. The hose has water pressure and the water will flow through the hose onto the passerby when you open the nozzle. Prior to spraying, though, you stop and think about the similarities between water flow in a hose and electrical current flow in a wire.

You know that a pump, operating somewhere, creates the water pressure in the hose, which is measured in pounds per square inch (psi). That water pressure places the water in a “Ready to Flow” state. Similarly, an electric generator creates an electromotive force (EMF), which is measured in volts. The electricity in the wire is in a “Ready to Flow” state and has a certain voltage or EMF.

Now if you open the nozzle of that water hose, the unsuspecting passerby will get drenched with a flow of water. That water flow gets described in gallons per minute (gpm). The electrical rate of flow is defined as Current (I) and gets measured in Amps. In order for a motor to turn or a light bulb illuminate, current must flow.

The third parallel between a water hose and an electrical wire concerns resistance. If you have several hundred feet of hose coiled at your feet that the water must pass through, not much water will emerge from the hose to spray that unsuspecting passerby. The head loss in the hose due to friction will greatly reduce the water flow and the water pressure. Similarly, resistance in an electrical circuit, either from a long wire not properly sized or an electrical device can reduce both EMF and current flow.

To recap, remember that the EMF (electromotive force measured in volts) is like the water pressure (psi), while the current flow (amps) is like the water flow (gpm).