In the four-band color code for a resistor, the third and fourth color bands are used to indicate:A. Resistance value: first and second digits
B. Resistor tolerance and engineering units
C. Resistor value multiplier and tolerance
D. Resistor value and tolerance
The answer is C, “Resistor value multiplier and tolerance.”
The first and second color bands are used to indicate a two-digit value. The third band indicates the multiplier. The fourth band indicates the tolerance. For example, if the first two bands are black and red, the corresponding value is “02.” If the third band is yellow, that represents a multiplier of 10K ohms. Therefore, the resistor with these band colors in these positions is a 2 × 10 K or 20 K ohm resistor. If the fourth band is violet, the resistor tolerance is ±0.1 percent.
Reference: Goettsche, L. D. (Editor), Maintenance of Instruments and Systems, Second Edition, ISA, 2005.
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