Elec Class
learn electricity hands-on
Solved exercise · level 3 of 5
Skills: Calculate
A copper wire (ρ = 1.7 × 10⁻⁸ Ω·m) is 500 m long with a cross-section of 4 mm². Compute its resistance.
l = 500 m · S = 4 mm²
Parametric exercise: the values change with every draw; these are one example.
Guided problem in 4 steps: unknown, formula, units, data, result.
S = 4 mm² = 4 × 10⁻⁶ m²; R = ρ·l/S = 1.7 × 10⁻⁸ × 500 / (4 × 10⁻⁶) = 2.13 Ω.