Electrical principles - Terminology

Electrical basics

One way to help understand how current, voltage and resistance work is to use an analogy. This means using something you already know and understand to help explain something new.

The diagrams show how water can be a useful analogy to help understand electricity.


Diagram showing electrical pressure comparison to water pressure


Analogy between water and electricity


Pressure – voltage

Figure 2 shows a full water tank. This is where the water pressure is stored. The greater the amount of water in the tank, the greater the water pressure. The water tank in Figure 2 can be compared to the battery in Figure 1, where a battery in an electrical circuit stores the electrical pressure (voltage).

An empty tank of water with no pressure is similar to a flat battery with no electrical pressure.


Flow – current

Turning on the tap in Figure 2 allows water, pushed out of the tank by pressure, to flow through the pipe and water wheel. This causes the wheel to rotate. Similarly, in Figure 1, turning on the switch allows current flow, pushed out of the battery due to electrical pressure, through the wire and globe.

The flow of water is similar to the flow of current (amps).


Restriction – resistance

The pipe size and wheel construction cause a restriction to the water flow. The restriction of water flow is similar to resistance in an electrical circuit. In Figure 1 the wire and globe offer a resistance to current flow. The size of the wire and the globe affect the amount of current flowing.



  • Water pressure stored in the tank is similar to voltage (electrical pressure) stored in a battery.
  • The flow of water through a pipe is similar to the flow of current through a wire.
  • The path the water flows along causes a restriction to flow.
  • The path the current flows through has a certain amount of resistance.