Welcome!

Welcome to the Simple Circuits project!

The interaction between voltage, current and resistance is really the heart of electronics, and we’ll be looking at their relationships in the coming lessons.  But first, let’s take a sneak peek at how circuits work, because circuits are how we control electricity—and how we get all the benefits from it that we enjoy.

Your success as a technician, engineer or hobbyist depends on your ability to analyze, modify and create circuits.

There’s so much to the electrical circuit that you’ll be building a lot of them—which is good, because it’s a lot of fun, especially when you throw the switch to see if it actually works.  But for now, let’s introduce you to some key concepts that you may have already picked up on in our animations and illustrations.

If you think that “circuit” sounds a lot like “circle,” well, you get extra points!  The word “circle” comes from the Latin word circus, which means “ring.”  (Now you can see why it’s called a “three-ring circus.”  Which, when you think about it, means “three-ring ring.”  But now you know.)

The word “circuit” also comes from Latin, and it means “to go around.”  And that is exactly what happens in all working electrical/electronic circuits:  electricity goes around in a circle.  And that is a very important concept to start with:

• For current to flow, there has to be an unbroken circle from a point of higher potential to a point of lower potential.
• If that circle is broken, current cannot flow—or it stops flowing if we break a previously working circuit.
• A switch is simply a controlled way to break a circuit—which is precisely what we need when we want to stop electricity from flowing in a circuit—like turning a light off when it’s time for bed.

For every circuit, you should be able to trace a path from a starting point with higher potential, along something that will conduct electricity to a point of lower potential.  A good way to tell if you understand a given circuit is to trace that path.  If you can’t trace it, you probably don’t understand it yet.