How do you determine resistance from a 4-band resistor color code?

• A. Fourth band = tolerance
• B. First two bands are digits, third band = multiplier, fourth band = tolerance
• C. Third band = multiplier, fourth band = tolerance, first two bands = digits
• D. First band = digit, second band = digit, third band = multiplier, fourth band = tolerance

Answer: (B)

When reading a four-band resistor, the digits come in a specific order: the first two bands are the digits that form the base number, the third band is the multiplier (a power of ten to multiply that base by), and the fourth band is the tolerance (how close the actual resistance is to the stated value). This means you take the two-digit number from the first two colors, multiply by 10^n from the third color, and note the tolerance from the fourth color.

For example, if the bands are brown, black, red, and gold: digits are 1 and 0, the multiplier is 10^2, so resistance is 10 × 100 = 1000 ohms, with a 5% tolerance. The order described matches the standard four-band code.