How-To Geek


Electronic Resistors Are Commonly Distinguished With What Markings?
Raised Dots
Unique Wire Leads
Serial Numbers
Colored Bands

Answer: Colored Bands

If you’ve ever peered closely at the resistors found on the guts of many of your household electronics, you may have noticed their tiny stripes. Those color bands, known formally as the Electronic Color Code, serve to indicate the resistor’s resistance value.

The system was developed in the 1920s by the Radio Manufacturers Association (an organization now known as the Electronic Industries Alliance) to help easily distinguish the values between otherwise often indistinguishable resistors. The color of the band and the order of the bands serve to indicate significant figures (the first two bands) of the resistor value, as well as the decimal multiplier (the third band), and the tolerance of the resistor (the fourth band). To a layman the band system seems quite arcane but to a well versed professional or serious hobbyist the band system is second nature.

While this system of color-coded bands has prevailed for the better part of a century now (and will likely continue to do so for non-surface resistors) the advent of tiny surface-mount resistors–often hardly bigger than a grain of rice–has led to an increase in alpha-numeric coding in place of the banding method.

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