Electricity and Electronics for Renewable Energy Technology

Appendix E: Standard Resistors

Resistors for electronic and small electrical circuits are made from various materials such as carbon film or metal film (a thin layer covering a supporting body) mostly in a cylindrical form with two leads coming out from the two ends of the cylinder for connection to other parts in a circuit. They come in different values and with a few power values (the maximum power they can dissipate). Resistance values can be as small as a fraction of 1 Ω to large values such as 10 M Ω (10 million ohm). There are three issues in understanding how to select a resistor: tolerance, magnitude, and power.

E1.1 Resistor Value Tolerance

The manufacturing process does not guarantee that a resistor has an exact value as desired. More ...