Engineering Board Exam Reviewer · Voltage, Current and Resistance · hard
A copper wire 50 m long has a resistance of 0.43, ( =1.72×10-8, · m). Find its diameter.
- 2 mm
- 0.8 mm
- 3.19 mm
- 1.6 mm
Answer
D. 1.6 mm
Solution
A= L/R= (1.72×10-8)(50)0.43=2.0×10-6 m2=2.0 mm2. Since A=π d2/4, d=sqrt(4A/π)=1.6 mm.
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