what the difference between a potentiometer and a variable resistor ?

 

A variable resistor is made up of a potentiometer wired with the center leg tied to one or the other end of the pot. This permits it to act like a variable resistor.

hgmjr

 

Here's a schematic to illustrate hgmjr's assertation.

When wired as a potentiometer, the wiper (usually the middle connection) acts as a tap. In the circuit on the left, Vout could be a voltage anywhere between +V and -V, depending upon the setting of the pot.

 

Another term used in place of variable-resistor is "rheostat" as mentioned by sgtwookie.

hgmjr

 

what the difference between a potentiometer and a variable resistor ?

A variable resistor is a two terminal component which you can vary its resistance by rotating an axis or by sliding a conduct along its axis (big one, usually used in labs for experiments).

A pot is a three terminal component which you can use as a variable resistor (as SgtWookie said) and to obtain a variable voltage on one of its pins by rotating its axis by your fingers (panel mounted pots, you can use them frequently) or by a screwdriver (trimmers, usually used on PCB's to adjust something for a few times because they fail if you use them frequently).

 

Hello,

More information on resistors and potmeters you can find here:
http://www.educypedia.be/electronics/resistors.htm

There are links about other components to:

Passive semiconductors technology: Batteries Diodes Photovoltaic systems Switches Buzzers Diode types Quartz crystals Thermoelectric Capacitors General overview Relays Transformers Capacitor types Heat Sinks Resistors Transformers-RF Coils Photo diode Resistors-Nonlinear Transformer types
Greetings,
Bertus