What does the color code on a resistor indicate?

• A. The date the resistor was manufactured
• B. The value of resistance in resistor
• C. The number of hours the resistor can function
• D. The number of minutes needed to discharge

Answer: (B)

Colors on a resistor form a code used to represent its resistance value in ohms without printing the number itself. In the common four-band style, the first two bands give the digits, the third band is the multiplier (how many zeros to add), and the fourth band shows the tolerance (how accurate the value is). The colors map to digits this way: black 0, brown 1, red 2, orange 3, yellow 4, green 5, blue 6, violet 7, gray 8, white 9. To read it, read the first two colors as a two-digit number, then multiply by 10 raised to the power specified by the multiplier color. The result is the resistance in ohms, with the tolerance band telling you the precision. For example, brown-black-red-gold represents 10 × 100 = 1000 ohms (1 kΩ) with 5% tolerance. Some resistors use five bands (three digits, then multiplier and tolerance) or include a temperature coefficient; the basic idea remains that the color code communicates the resistance value, not manufacture date or operational time.