On a resistor color code, what digit does the color yellow represent?

• A. 2
• B. 4
• C. 7
• D. 3

Answer: (B)

Colors on a resistor correspond to digits in a fixed sequence: black 0, brown 1, red 2, orange 3, yellow 4, green 5, blue 6, violet 7, gray 8, white 9. Yellow is the fifth color in that order, so it represents the digit four. Therefore the digit represented by yellow is four. The other options map to red (2), violet (7), and orange (3), which are different colors.