Electrical circuit symbols

Lamp

An electrical current heats the filament in a bulb so that it gives out light.

Voltmeter

the voltmeter measures voltage (potential difference) across two points.

Ammeter

Used to measure the current in a circuit

LDR

resistor whose resistance decreases with increasing light intensity

Thermistor

The resistance of a thermistor depends on its temperature. At low temperatures, the thermistor has a high resistance. As the temperature increases, the resistance decreases.

Variable resistor

Moving the position of the slider on this resistor, changes the resistance. A variable resistor is used in some dimmer switches and volume controls.

Diode

a circuit component that only allows current to flow in one direction

LED

a light-emitting diode

Fuse

breaks the circuit if a fault in an appliance causes too much current to flow

Cell

An electrical cell converts chemical energy into electrical energy, allowing current to flow from positive to negative terminals.

Battery

A device that stores and provides electrical energy through a chemical reaction, consisting of one or more cells connected together.

Closed switch

A switch that allows current to flow through a circuit when in the 'on' position.

Open switch

A switch that prevents current from flowing through a circuit when in the 'off' position.