Symbols are used in drawing circuits instead of drawing pictures. It is complicated and confusing to draw pictures to show someone, how a circuit is connected up. Also, it is time consuming. So, we use circuit symbols to draw circuits in order to overcome these problems. In this lesson you’ll be able to know some of the circuit symbols that we use in drawing circuits.
A symbol is a sign, letter or diagram that represents or stands for something. For example in circuit drawing we use many symbols. To show a bulb or lamp we use following symbol;
1) It saves time.
2) It is a good way of showing someone how a circuit should be connected up.
Examples of circuit symbols used in drawing circuits
Examples of drawings of a simple circuit with a bulb, cell and the switch
Example of a simple circuit with the switch ON
Example of a simple circuit with the switch OFF
Example of a simple circuit with two bulbs with the switch ON
Look at each circuit diagram below. Which one do you think the bulb or bulbs will light.
One of the ends of a cell to which the wires must be connected in a circuit is called a terminal of a cell.
1) Negative terminal (-)
2) Positive terminal (+)
Electricity flows from the negative terminal (-) to the positive terminal (+) of the cell.
Why? Because, first we must join the two terminals of a cell by a material that conducts electricity.
Positive and Negative Terminals of a cell
The long vertical line
The short vertical line
Symbolic representation of Terminals of a cell