Carbon resistor colour code — meaning of the third band (multiplier) In the standard 4-band colour code for carbon resistors, the third band is red. What does this indicate?

Introduction / Context:Resistor colour codes encode the nominal resistance and tolerance. In a 4-band scheme, the first two bands give significant digits, the third band is the multiplier (a power of ten), and the fourth band is tolerance.

Given Data / Assumptions:

• 4-band carbon composition or film resistor.
• Third band colour is red.
• Standard EIA colour mapping applies.

Concept / Approach:The colour-to-number mapping is: black 0, brown 1, red 2, orange 3, yellow 4, green 5, blue 6, violet 7, grey 8, white 9. As a multiplier, the third band represents 10^(colour number). Red corresponds to 10^2, meaning “add two zeros” after the first two significant digits.

Step-by-Step Solution:Map red → 2.Multiplier = 10^2.10^2 means two trailing zeros when writing the resistance value.Therefore, the third red band indicates “two zeros”.

Verification / Alternative check:Example: yellow-violet-red-gold → 47 × 10^2 = 4.7 kΩ ±5%.

Why Other Options Are Wrong:(b) “three zeros” corresponds to orange (10^3); (c) 0.01 and (d) 0.1 are multipliers for silver (10^−2) and gold (10^−1) respectively, not red.

Common Pitfalls:Reading from the wrong end; confusing 5-band code (three significant digits) with 4-band code.

Final Answer:two zeros