Resistor
From Electronics Wiki
A resistor is a passive, two-terminal electronic component, that when connected in series in a circuit, constrains the flow of current.
It produces a voltage drop between its terminals in proportion to the resulting current; that is, in accordance with Ohm's law: .
The electrical resistance R is thus equal to the voltage drop V across the resistor divided by the current I through the resistor.
Resistors are used as part of electrical networks and electronic circuits.
As with many electronic components, resistors can have fixed values or variable values. Typically when a resistor is referred to as a "resistor" then it is implicitly a fixed value resistor. Variable resistors are more often referenced by more specific names like potentiometers (or just pots), trimmer potentiometers (aka trimpots), or rheostats.
While fixed resistors are nearly always internal components on electronic devices, variable resistors are often part of user interface features such as control knobs and sliders.
Resistor values are identified by colour codes.
- http://www.electronics-tutorials.ws/resistor/res_1.html tutorial on resistors
- http://www.elexp.com/t_resist.htm resistor colour codes
