In a standard resistor color code, which band combination represents 100 ohms?

• A. Red Red Red
• B. Brown Black Brown
• C. Orange Orange Brown
• D. Yellow Violet Gray

Answer: (B)

Two left bands are the significant digits, and the third band is the multiplier. Brown represents 1 and Black represents 0, so the digits are 10. The multiplier brown means 10^1, so 10 × 10 = 100 ohms. This is how a 3-band resistor value is read: the first two bands give the digits, and the third band scales them. The other options yield different values (for example, red-red-red would be 22 × 10^2 = 2,200 ohms, orange-orange-brown is 33 × 10^1 = 330 ohms, etc.), so Brown-Black-Brown correctly equals 100 ohms.