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Resistor Color Codes

Resistors are small electronic parts that resist the flow of electrical current. Resistors have many uses, and you can find them in many Science Buddies electronics projects. A resistor's amount of opposition to the flow of current is called its resistance. Resistance is measured in ohms, abbreviated Ω (the capital Greek letter Omega). Resistance may have a metric prefix, for example kilo-ohms (kΩ). One kilo-ohm is equal to 1,000 ohms.

The resistance value is indicated by color-coded bands on the resistor. You can identify the resistance of a four-band resistor using the following table. The first two bands are the base resistance value, the third band is a power of 10 multiplier, and the fourth band (which is spaced farther away from the other three bands) is the tolerance.

Color 1st band (1st digit) 2nd band (2nd digit) 3rd band (multiplier) 4th band (tolerance)
Black 0 0 ×100 
Brown 1 1 ×101 ±1%
Red2 2 ×102 ±2%
Orange 3 3 ×103 ±3%
Yellow 4 4 ×104 ±4%
Green 5 5 ×105 ±0.5%
Blue 6 6 ×106 ±0.25%
Violet 7 7 ×107 ±0.1%
Grey 8 8 ×108 ±0.05%
White 9 9 ×109  
Gold    ×10-1 ±5%
Silver   ×10-2 ±10%

So, for example red, red, brown, gold indicates 22×101 ± 5% = 220Ω ± 11Ω. Brown, black, orange, gold indicates 10×103 ± 5% = 10kΩ ± 500Ω:

Resistance Band colors Image
220 Ω Red, red, brown, gold 220 Omega resistor
10 kΩ Brown, black, orange, gold 10k Omega resistor

Using the table above, can you identify the resistances of the resistors in this picture?

an assortment of resistors
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