VARIABLE RESISTOR

A variable resistor has a movable contact that is used in selecting the required resistance. Potentiometers have markings on them; these markings indicates the maximum value in which the potentiometer can be adjusted to.

Recognising markings on variable resistors:

A variable resistor marked 10K means that its range of resistance is 0 to 10,000 ohms.
If it is marked 104, the resistance will be 10 x10^4 = 100,000 ohms.
If it is marked 103, the resistance will be 10 x10^3 = 10,000 ohms.

Variable resistors are of either the slide type or the rotary(dial) type.

 

Consider the variable resistor below to be 100K ohms:

Measuring the resistance between pin 1 and 3 will give the maximum value of the resistor which in this case is 100,000 ohms. Measuring between pin 1 and 2 or between pin 2 and 3 will give 50,000 ohms in either case because pin 2 gave been set to exactly 50%.
Adjusting pin 2 anti-clockwise will reduce the resistance between pin 1 and 2 and increase the resistance between pin and 3. Reverse is the case when pin 2 is adjusted in clockwise direction.