1.3: What Are Electric Circuits?

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What Is a Circuit?

The answer to this paradox is found in the concept of a circuit: a never-ending looped pathway for electrons. If we take a wire, or many wires, joined end-to-end, and loop it around so that it forms a continuous pathway, we have the means to support a uniform flow of electrons without having to resort to infinite Sources and Destinations:

Each electron advancing clockwise in this circuit pushes on the one in front of it, which pushes on the one in front of it, and so on, and so on, just like a hula-hoop filled with marbles.

Now, we have the capability of supporting a continuous flow of electrons indefinitely without the need for infinite electron supplies and dumps. All we need to maintain this flow is a continuous means of motivation for those electrons, which we’ll address in the next section of this chapter on voltage and current.

What Does It Mean When a Circuit Is Broken?

Continuity is just as important in a circuit as it is in a straight piece of wire. Just as in the example with the straight piece of wire between the electron Source and Destination, any break in this circuit will prevent electrons from flowing through it:

An important principle to realize here is that it doesn’t matter where the break occurs. Any discontinuity in the circuit will prevent electron flow throughout the entire circuit. Unless there is a continuous, unbroken loop of conductive material for electrons to flow through, a sustained flow simply cannot be maintained.

Review

A circuit is an unbroken loop of conductive material that allows electrons to flow through continuously without beginning or end.
If a circuit is “broken,” that means its conductive elements no longer form a complete path, and continuous electron flow cannot occur in it.
The location of a break in a circuit is irrelevant to its inability to sustain continuous electron flow. Anybreak, anywhere in a circuit prevents electron flow throughout the circuit.