What is the difference between a fixed resistor and variable resistor?
Variable resistors means that a resistor can change its resistance value through the control of a person or himself. Fixed resistance means that it cannot change its value.
The fixed resistance has only one value and never changes (except through temperature, age, etc.). Examples are carbon composition resistors, wire resistors, thin film resistors, thick film resistors.
There are three types of variable resistors. Potentiometer, rheostat and trimmer.
There is an additional screw with a potentiometer or variable resistors for better efficiency and operation. These are called trimmers.
The resistance value can be changed by changing the position of the screw to turn it with a small screwdriver.
An example of a potentiometer is the volume control of your radio, and an example of the rheostat is the dimmer control for the dashboard lighting in a car. There is a little difference between them.
Rheostats usually have two connections, one fixed and the other movable. Every variable resistance can be called a rheostat.
The potentiometer always has three connections, two fixed and one movable. In general, the rheostat has a limited range of values and a high current carrying capacity.
The potentiometer has a wide range of values, but is normally only able to handle electricity to a limited extent. Potentiometers are always connected as voltage dividers.
A fixed resistance gives you a fixed resistance value that does not change significantly (but changes negligibly). You can change the resistance while in a variable resistor.
The variable resistance indicates different values depending on the state and the permissible current flow.