How do we identify the value of resistance on a fixed resistor?

How do we identify the value of resistance on a fixed resistor?

• A. Numeric engraving on the body
• B. Color bands on the resistor
• C. Color code on the packaging
• D. Digital display on the resistor

Answer: (B)

Color bands on the resistor body encode the resistance value. In the common four-band style, the first two bands are the significant digits, the third band is the multiplier (the power of ten to multiply those digits by), and the fourth band indicates tolerance. Some resistors use a five-band code, where three bands provide the digits, the fourth is the multiplier, and the fifth is tolerance. The color-to-digit map is standard: black 0, brown 1, red 2, orange 3, yellow 4, green 5, blue 6, violet 7, gray 8, white 9. The multiplier uses the same color scale (for example red means ×100). Tolerance is typically shown by the last band, commonly gold (±5%) or silver (±10%). For example, brown-black-red-gold reads as 10 with a multiplier of 100, giving 1000 ohms (1 kΩ) with ±5% tolerance. Another common case, red-violet-brown-silver, equals 27 × 10 = 270 ohms with ±10% tolerance. Engraving on the body or color codes on packaging aren’t the standard way to read the value on a fixed resistor, and there isn’t a digital display on the resistor itself. The color bands on the resistor are the reliable identifiers of its resistance.

Color bands on the resistor body encode the resistance value. In the common four-band style, the first two bands are the significant digits, the third band is the multiplier (the power of ten to multiply those digits by), and the fourth band indicates tolerance. Some resistors use a five-band code, where three bands provide the digits, the fourth is the multiplier, and the fifth is tolerance. The color-to-digit map is standard: black 0, brown 1, red 2, orange 3, yellow 4, green 5, blue 6, violet 7, gray 8, white 9. The multiplier uses the same color scale (for example red means ×100). Tolerance is typically shown by the last band, commonly gold (±5%) or silver (±10%).

For example, brown-black-red-gold reads as 10 with a multiplier of 100, giving 1000 ohms (1 kΩ) with ±5% tolerance. Another common case, red-violet-brown-silver, equals 27 × 10 = 270 ohms with ±10% tolerance.

Engraving on the body or color codes on packaging aren’t the standard way to read the value on a fixed resistor, and there isn’t a digital display on the resistor itself. The color bands on the resistor are the reliable identifiers of its resistance.