For a 4-band resistor with colors brown, red, yellow, gold, what is the maximum resistance value when tolerance is included?
Electrical Engineering
Voltage, Current and Resistance
Difficulty: Easy
Choose an option
-
A126,000 Ω
-
B126,600 Ω
-
C114,000 Ω
-
D132,000 Ω
Answer
Correct Answer: 126,000 Ω
Explanation
Introduction / Context:Component tolerances define allowable variation from nominal values. Reading the color code and then applying tolerance limits helps you evaluate worst-case circuit performance and ensure designs remain within specification.
Given Data / Assumptions:
- Bands: brown (1st), red (2nd), yellow (multiplier), gold (tolerance).
- Gold tolerance = ±5%.
Concept / Approach:Digits: brown = 1, red = 2 → '12'. Multiplier yellow = 10^4. Nominal value R_nom = 12 * 10^4 = 120,000 Ω. Maximum value R_max = R_nom * (1 + tolerance).
Step-by-Step Solution:
Compute R_nom: 12 * 10^4 = 120,000 Ω.Tolerance: ±5% → maximum = 120,000 * 1.05.R_max = 126,000 Ω.Verification / Alternative check:Minimum would be 120,000 * 0.95 = 114,000 Ω. This brackets the tolerance band and confirms the calculation of the maximum value as 126,000 Ω.
Why Other Options Are Wrong:
- 126,600 Ω: Incorrect arithmetic for +5% of 120,000 Ω (should be +6,000 Ω, not +6,600 Ω).
- 114,000 Ω: That is the minimum value (−5%), not the maximum.
- 132,000 Ω: Would correspond to +10%, not +5%.
Common Pitfalls:
- Mistaking yellow (10^4) for orange (10^3), which would change the nominal value completely.
- Applying tolerance to the color digits rather than to the computed nominal resistance.
Final Answer:126,000 Ω