In a circuit with an alternating current, a diode lets forward current through, but it blocks the reverse current. This is called rectifying the current.
To identify its value, each resistor is marked with four or five colored bands. Each color represents a number value, so by reading the color values it is possible to identify its resistance value.
Some resistors found in the motor vehicle are variable. Variable resistors can have their value altered by movement of a slide or by temperature change.
Thermistors are semiconductor resistors. Their resistance changes according to their temperature and they are used to control many electrical items in the automobile.
