Which color band represents the tolerance in the 100 ohm resistor example?

• A. Gold
• B. Silver
• C. Red
• D. Brown

Answer: (A)

Color bands on resistors tell you not only the resistance value but also how precise it is. In the common four-band code, the first two bands are the digits, the third is the multiplier, and the fourth shows tolerance. For a 100-ohm resistor, the digits are 1 and 0 (brown and black), the multiplier is brown (×10), so 10 × 10 = 100 ohms. The last band indicates tolerance, and in this typical example that band is gold, which means a tolerance of ±5%. So gold represents the tolerance. If you saw silver, that would be ±10%; red would be ±2%; brown would be ±1%—these reflect different tolerance levels, not the one shown in this particular 100-ohm example.