Which color bands represent a 1 kΩ resistor with ±5% tolerance using a 4-band code?

• A. Brown-Red-Black-Gold.
• B. Brown-Black-Red-Gold.
• C. Red-Brown-Black-Gold.
• D. Brown-Black-Gold-Red.

Answer: (B)

In a 4-band resistor code, the first two bands are the significant digits, the third is the multiplier (the power of ten to multiply those digits by), and the fourth band is the tolerance. To get 1 kΩ, which is 1000 Ω, you want the digits 1 and 0, then multiply by 10^2. The color for 1 is brown, for 0 is black, and the multiplier 10^2 is red. A tolerance of ±5% is shown by gold. So the color sequence is brown, black, red, gold.

That sequence specifically encodes 1000 Ω with 5% tolerance. Other shown sequences would encode different values: for example, brown-red-black-gold would be 12 Ω, red-brown-black-gold would be 21 Ω, and brown-black-gold-red would be 1 Ω with ±2% tolerance.