BASIC TECHNOLOGY LESSON NOTE: Simple Electrical Wiring – Schematic Diagram

An electric circuit is an arrangement of conductors for the purpose of carrying current.

However, before electric current can flow in a circuit, two conditions must be met; namely:

1.        There must be a source of electromotive force (emf) to overcome the resistance of the circuit, and so drive the current round it.

2.        There must be a complete path of conducting materials through which the current can flow.

schematic diagram is a representation of the elements of a system using abstract graphic symbols rather than realistic pictures.

An electric circuit diagram is a schematic diagram in the sense that symbols are used to depict various components of an electric circuit.

Class activity:

Identifying some electrical accessories:

xpinoBLOG battery


Types of schematic (circuit) diagrams

There are two classes of circuit diagrams, namely:

1.                  Series circuit; and

2.                  Parallel circuit

Series circuit

In a Series circuit, the same current flows from the positive terminal of the battery through all the bulbs. However, fault in one bulb will affect others because current will not get to the other parts of the circuit. All the accessories share same current, so if the accessories (e.g. buld) are increased without increasing the current reduces the current flowing through each accessory. (PRACTICAL CLASS for confirmation)

Parallel Circuit

In a Parallel circuit, each device is placed in its own separate branch. The presence of branch lines means that there are multiple pathways by which charge can traverse the external circuit.

Class activity:

In tabular form, state at least two major differences between series and parallel circuits in your notebook.


1.             What is an electric circuit?

2.             What is a schematic diagram?

3.             What is an electric circuit diagram?

4.             What are two conditions that must be met before electric current can flow in a circuit?

5.             What are the symbols of some common electrical accessories?

6.             What are the major differences between series and parallel circuits?


1.             List 5 tools used in electrical wiring.

2.             List 5 accessories used in the wiring of a house.

3.             List four materials used in house wiring.


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