Resistor color code practice: Determine the correct 4-band color code for a 3.9 kΩ resistor with a ±5% tolerance.

Introduction / Context:
The 4-band resistor color code encodes two significant digits, a power-of-ten multiplier, and a tolerance band. Fluency with the code allows quick identification of components during prototyping and troubleshooting without consulting a datasheet.

Given Data / Assumptions:

• Target value: 3.9 kΩ = 3900 Ω.
• Format: 4 bands → digit1, digit2, multiplier, tolerance.
• Assume common ±5% tolerance for general-purpose resistors (gold).

Concept / Approach:
Color mapping (digits): black 0, brown 1, red 2, orange 3, yellow 4, green 5, blue 6, violet 7, gray 8, white 9. Multiplier: red = ×10^2, orange = ×10^3, etc. 3.9 kΩ has significant digits 3 and 9, then a multiplier of ×10^2 to yield 39 × 10^2 = 3900 Ω. Tolerance gold = ±5%.

Step-by-Step Solution:

Verification / Alternative check:
Cross-check by reconstructing value: 3 9 with multiplier ×10^2 = 3900 Ω = 3.9 kΩ; tolerance ±5% gives range 3.705 kΩ to 4.095 kΩ, which matches common E24 series availability.

Why Other Options Are Wrong:

• Red, white, red, gold: 2 9 × 10^2 = 2.9 kΩ, not 3.9 kΩ.
• Red, green, orange, silver: 2 5 × 10^3 = 25 kΩ, tolerance ±10% (silver).
• Orange, green, orange, silver: 3 5 × 10^3 = 35 kΩ, tolerance ±10%.

Common Pitfalls:
Reading the bands from the wrong end (tolerance band is spaced farther apart), or confusing white (9) with silver (tolerance). Always locate the tolerance band first to set the reading direction.

Final Answer:
orange, white, red, gold