A wide variety of resistors are physically large enough to have their resistance value printed on them. However, carbon composition resistors are too small for this method of identification so a color coding system is used. Four bands are printed on one end of the resistor and are read from the band closest to the end of the resistor toward the center. Each color represents a numerical value as indicated below.
Suppose the color bands of a resistor are yellow, violet, red and gold. The resistance value is determined as follows:
4 7 00 = 4700Ω
Yellow = 4
Violet = 7
Red = 2 (two zeros)
Gold = ±5%
4700+5% = 4935} The actual resistance should be between 4467 and 4935 ohms.
4700-5% = 4465}
Occasionally a fifth band is used to indicate the failure rate of the resistor:
Yellow 0.001% per 1000 hours
Orange 0.01% per 1000 hours
Red 0.1% per 1000 hours
Brown 1.0% per 1000 hours
