The following symbols show the different components that can be found in an electrical circuit.
Some of the more common components are:
A switch is used to turn a circuit on (closed switch) and off (open switch).
The resistance of this resistor is changed by moving the position of a slider. A variable resistor is used in some dimmer switches and volume controls.
Light-dependent resistor (LDR)
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. A thermistor can be used in thermostats or heat-activated fire alarms.
The resistance of a LDR depends on light intensity. At low light levels, the LDR has a high resistance. As the light intensity increases, the resistance decreases. An LDR can be used as a sensor in cameras or in security lights that come on automatically when it gets dark.