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Circuit Symbols

Circuit diagrams are used to show how electrical components are connected together. Each electrical component has its own symbol. In order to draw basic circuit symbols it is important you learn the following symbols.

Component Symbol Function
Wire
Made from a metallic conductor so current can easily pass from one part of the circuit to another
Switch (open)
On/Off switch – in open position the circuit is broken so no current flows
Switch (closed)
On/Off switch – in closed position the circuit is complete and current flows
Cell
Supplies the electrical energy to the circuit – the larger terminal on the left is the positive (+) terminal
Battery
A battery is more than one cell.
Lamp
Coverts electrical energy to light.
Fuse
A safety device which melts to break the circuit if the electrical current flowing through it exceeds a specified value.
Voltmeter
Instrument used to measure potential difference.
Ammeter
Instrument used to measure electrical current
Resistor
Restricts the flow of electrical current can be used to limit the flow of current to a particular component
Diode
A device which only allows current to flow in one direction
Thermistor
Converts heat to electrical resistance
Variable resistor
Used to control current
Light dependant resistor
Converts light to electrical resistance