Resistors
A linear resistor is a linear, passive two-terminal electrical component that implements electrical resistance as a circuit element. The current through a resistor is in direct proportion to the voltage across the resistor's terminals. Thus, the ratio of the voltage applied across a resistor's terminals to the intensity of current through the circuit is called resistance. This relation is represented by Ohm's law:
(sorce: Wikipedia)
Axial-lead resistors (left side) and power resistors (right side)
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Resistor Colour-code:
Testing:
Resistor can be tested with ohmmeter by connecting two terminals to the meter.
Potentiometers
Potentiometer is 3 terminal resistor with sliding wiper that forms an adjustable voltage divider. Potentiometer can be easily turned in to rheostat (or variable resistor) by using just 2 terminals: one side of the resistor and wiper. Applications: volume control in sterio systems, some car sensors (TPS, AFM).
In time potentiometers wear out and become noisy.
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