Electric circuit symbols

Have you ever seen an electrical circuit diagram? These diagrams sometimes come with new appliances or may be glued to the inside of appliances to inform electrical repairers. Have you wondered what the symbols on the diagrams mean? Scientists and engineers have developed a set of symbols to represent the components of an electric circuit. This makes it simpler to show how the various components of a circuit are wired together. It means that using standard symbols can describe to anyone familiar with electrical circuits either how an existing circuit has been constructed or can act as a blueprint for telling someone how a circuit should be built.

Electrochemical cell – Long, thin side is POSITIVE terminal, shorter, thicker side is NEGATIVE terminal 

or        

Battery – A number of electrochemical cells attached together

Variable DC Power supply

An open switch, i.e. the circuit is switched OFF.

A closed switch, i.e. the circuit is switched ON.

Conductor wire – made of metal and used to attach components together

Light globe

or

A fixed resistor – a device which offers a particular electrical resistance

An ammeter used to record the size of the electric current flowing in wires. Attached in series in circuit.

 A voltmeter used to record the voltage drop between two points, (the change in energy for each coulomb of charge). Attached in parallel in circuit.

Electrical contacts to allow the connection of another device between them

Connected together in a circuit

This simple circuit shown below contains the common components of any electric circuit, i.e. the battery acts as the power supply to provide the energy to operate the circuit; the conducting leads allow the electric current to flow from the battery; the switch can complete the circuit when closed or break the circuit when open; the light globe is the load where the electrical energy is converted into other forms, e.g. light and heat. 

This circuit diagram below represents the components in the above circuit. 

You can use an online circuit builder to design and test simple circuits at www.circuitlab.com or visit the interactive learning guide, download circuit construction kit (parts 1 and 2) or try and make your own circuits from electrical components.