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A resistor is a component that opposes or impedes the flow of electrons through it. Thus, it limits the current flow in a circuit. A resistor can also be used to reduce the voltage. All resistors have two basic ratings, their electrical value, expressed in ohms, and their power rating, expressed in watts. The wattage rating of a resistor is a measure of how much power it can handle without being damaged by heat and it has no bearing on the resistance value. The electrical value of a resistor is a measure of its voltage drop divided by the current flowing through it (R = E/I). There are many kinds of resistors and they appear in any mumber of shapes and sizes. The most widely used method of resistor identification is designating the value by means of a color code. Three examples of the most common types of fixed carbon resistors are shown in the figure below.

Fixed Carbon Resistors Types

A. Axial Leads B. Radial Lead Dot C. Radial Lead Band
resitype1.gif resitype2.gif resitype3.gif

Resistor Color Code Table

Click here for a resistance calculator!

Gold 0.15%
Silver 0.0110%
No color  20%

Last modified: Feb 15, 2016 20:14
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