Electrical mathQuestion 833 of 1506

A 240 V source feeds a load that needs at least 228 V. The load current is 20 A. What is the largest total resistance allowed for the supply and return wires together?

0.6 Ω
0.3 Ω
1.2 Ω
11.4 Ω

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Correct answer: 0.6 Ω

Allowed drop = 240 − 228 = 12 V. R = E/I = 12 V / 20 A = 0.6 Ω for both wires together.

Source: Lessons in Electric Circuits I: DC (Kuphaldt), 12.5: Specific Resistance

Questions last reviewed: 18 October 2026

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