Red Seal Electrician Practice
DC circuitsQuestion 1379 of 1506

A copper conductor measures 100 Ω at 20 °C. What is its resistance at 90 °C? Use 0.004041 per °C for copper.

  1. 71.713 Ω
  2. 28.287 Ω
  3. 136.369 Ω
  4. 128.287 Ω
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Correct answer: 128.287 Ω

R = R20 × (1 + α × ΔT) = 100 × (1 + 0.004041 × 70) = 128.287 Ω.

Source: Computed, 12.6: Temperature Coefficient of Resistance

Practice dc circuits

Questions last reviewed: 18 October 2026