Resistors can be either linear or non-linear. Linear resistors have resistance values that do not change with applied voltage, temperature, or light intensity. They include fixed resistors like carbon composition, thin film, thick film, and wire wound resistors. Non-linear resistors have resistance values that change under these conditions, including thermistors, photo-resistors, and varistors. Fixed resistors come in carbon composition, thin film, thick film, and wire wound varieties, and have resistance values that do not change. Variable linear resistors include wire wound resistors, potentiometers, and trimmers, and are used to control current flow.

1. Resistors

4. Linear Resistors
Resistors through which the current is directly proportional to the applied voltage, are called
linear resistors.
Such resistors have a property that their resistance values do not change with the variation in
applied voltage, temperature or light intensity.
The linear resistors are of two types, Fixed and variable.
Non Linear Resistor
Resistors through which the current is not directly proportional to the applied voltage, are called
non- linear resistors.
Such resistors have a property that their resistance values change with the variation in applied
voltage, temperature or light intensity.
The non-linear resistors are of three types, Thermistor, Photo-resistor and varistor.
Resistor
Linear
Fixed
Carbon Composition
Thin Film
Thick Film
Wire Wound
Variable
Wire Wound
Potentiometer
Trimmer
Non Linear
Thermistor
Photo Resistor
Varistor

5. Fixed Resistor
These are resistors whose values do not change with variations in applied voltage, temperature
and light intensity and they do not have the provision to change by their construction also.
These are available with Radial and Axial leads.
Fixed Resistor
Fixed Resistors are of 4 types
Carbon composition
Thin film
Thick film
Wire wound
Carbon Composition Resistor
Thin Film Resistor
Thick Film Resistor
Wire-wound resistors
Nichrome wire on a ceramic film
The wire is coated with an insulated material.
Variable Linear Resistors
Used to control current flow and provide desired amounts of voltage in electric circuits.
The values are varied from 0 to a specific value.
Types
Wire wound
Potentiometer
Trimmer
Wire wound
Wire wound on a ceramic core and covered with an insulated coating

6. Potentiometer
3 terminal variable resistor
Wiper connected to control shaft.
Movement provides a continuous variation in resistance between middle terminal and either
outside terminal.
Trimmer