A copper cable needs to carry a current of 200 A with a power loss of only 3.0 W/m. What is the required radius of the copper cable? (The resistivity of copper is 1.7 ´ 10-8 W×m.)
1) 0.21 cm
2) 0.85 cm
3) 3.2 cm
4) 4.0 cm
5) 4.7 cm
Answer: 2) 0.85 cm
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