Variable Resistors

Could somebody please tell me what the difference is between a linear and log. variable resistor please. Also why do variable resistors have 3 outputs? I only use 2 --- is this wrong?

Thankyou.

The resistance of linear potentiometer (or variable resistor) varies linearly with wiper movement whereas that of log. pot. varies on a logarithmic scale.

Pot. has three terminals. The resistance between end terminals is fixed whereas the centre terminal which is connected to the wiper has variable resistance with either of the fixed resistance end terminals.

In most applications, one fixed terminal and the wiper are shorted thereby forming a two terminal variable resistor.

Thank you

Thank you for your reply. It was very helpful.