Series vs. Parallel Circuits - The Basics

Circuits, although small, are what drives our electric world. From the lights in your house to the blender in the kitchen, circuits can be found in a variety of objects.

General information

There are three main components of circuits;

  1. A power source

  2. A wire

  3. Something to be powered.

Let’s use a light bulb for example.

We can draw these components in a simple circuit diagram like this.

There are electrons stored in the battery. These electrons get charged up in the battery then move along the wire to the light bulb. All the energy in the electrons are deposited at the light bulb which turns it on!

The electrons then travel back to the battery to recharge and the cycle continues.

Series circuits

This circuit is a perfect example of a series circuit. All the components are on one line and a break in any part of the circuit will cause the light to switch off. This is because electrons cannot flow through a broken circuit.

If a light bulb is added, in series, to a circuit, the brightness of the light bulb will decrease as though it is shared between the two bulbs.

Series circuits are used in small simple appliances as there is not much control over the circuit.

Parallel circuits

In a parallel circuit, the components can be along different lines as in the diagram below.

In this circuit, breaks do not necessarily cause the light bulb to turn off.

If there was a break in the circuit at the red point, light bulb B would remain on while light bulb A turns off.

This is because electrons can flow through the wire and deposit energy to light bulb B and continue back to the battery to get recharged.

Additionally, if more light bulbs are added in parallel, the brightness of the light bulb stays the same and does not dim.

This type of circuit is commonly used in complex objects that need more control. For example the lights in your home.

This makes it so turning on the lights in your room will not turn on the lights in the whole house.

That's it for the basics of series circuits and parallel circuits!

Have a look at some of the items in your household and predict the circuits used!

For more study tips and tricks, check out our other blog posts at

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