Basic Knowledge of Electrical Symbols
In our house, we use lights, fans, fridge, TV etc. These are all electrical appliances.
We connect all these devices to a plug point. Plug point acts as the source of electricity.
Any electrical appliance will work only when it is connected to an electrical source like a battery.
is a closed-loop which has a battery, some electrical elements and some connecting wires.
For the sake of understanding let’s see a simple light bulb and its circuit.
In this circuit, there is a small light bulb, a battery and a switch connected with some wires.
Here the light is glowing because the switch is on and the circuit is closed and electricity is flowing.
Every time we want to talk about this circuit we can’t use this image. It becomes tedious. So scientists needed a simpler method.
Rather than representing the electrical elements with images, scientists came up with the idea of symbols.
Now let’s see what are some electrical elements and their symbols.
Here is the symbol of an electric cell. In this symbol, the longer bar represents the positive terminal, the smaller bar is negative terminal.
A resistor is anything that consumes energy. Here is the symbol of a resistor. Example of a resistor is a bulb.
This is the symbol of electric bulb. The inside coil-like structure is the filament. The round circle is the glass around the filament.
Here are the symbols of switch on and switch off positions of the switch.
A battery is either a collection of cells or an energy with more voltage than a cell. Symbol is as shown.
Connecting wires symbol is as shown. Just a line connecting two elements.
Now we can use these symbols to represent a circuit easily without showing an actual battery and bulb every time.
Here is the representation of simple bulb, battery and switch circuit in symbols.
Here the position of the switch does not matter. It can be anywhere in the circuit.
It doesn’t matter because if the switch is open the circuit is not a closed-loop, so nothing in the circuit works.
Here the light doesn't glow as the switch is off and the circuit is open.
Only when it is closed, the circuit is a loop so everything is connected. Now the circuit is in on state and the bulb glows.
These are some basic symbols.