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THE SERIES CIRCUIT

After reading this section you will be able to do the following:

  • Define a series circuit, and list the components needed to make it.
  • Construct a simple and complex series circuit.
  • Define what a load is.

Try building this simple series circuit

In the interactive box (applet) below, you will need to place the correct circuit components (i.e. battery, light bulb, etc.) on the correct diagram symbol by dragging them with your mouse.

Congratulations! You have just built an electric circuit. Notice that when you close the switch to complete the electrical circuit, the electrons start moving and the ammeter indicates that there is current flowing in this circuit. Also notice that the light bulb begins to glow. This happens because the electrons moving through the tiny wires in the bulb (or filament) make them become so hot that they glow. If there is any air inside the light bulb, the filament wires will burn up.

What you have just created is something called a series circuit. This is called a series circuit because there is only one path for the electrons to take between any two points in this circuit. In other words, the components, which are the battery, the switch, the ammeter, and light, are all in “series” with each other.

Load defined

The light bulb is considered a load in this circuit. You might think of a load as anything that is using the energy that is being delivered by the electric current in a circuit. It could be anything from a light bulb to a computer to a washing machine and so on.

Try building a series circuit with resistors

Let’s build another series circuit, but this time we will use some resistors instead of a light bulb. Resistors are components that are used to control that amount of current flowing in a circuit. The light bulb in the first circuit was actually acting like a resistor because it only allowed a certain amount of current to flow through it. If there are no resistors or components that act like resistors to slow the flow of electrical current, too much current may flow through the circuit and damage its components or wires. Too much current flowing through a component results in the generation of heat that can melt the conductive path through which the electrons are flowing. This in known as a short circuit and is the reason fuses or circuit breakers are often included in a circuit.

Congratulations! You have just build a more complex series circuit. We cannot see any work being done since there is no light bulb, but there is current actually flowing inside. We know the current is flowing because the ammeter is indicating this. It is important to know that we may not be able to tell whether current is flowing through a circuit without test equipment, such as our ammeter connected to the circuit. Electricity can be very dangerous and experiments like these should never be conducted without adult supervision. Never work with electricity unless you are trained to know how to work with it safely.

Review

  1. When all the components are in line with each other and the wires, a series circuit is formed.
  2. A load is any device in a circuit that is using the energy that the electron current is delivering to it.