PhysicsCurrent electricityJAMB
A wire of resistance R is replaced by a wire of the same material with twice the length and half the cross-sectional area. Its resistance is
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Answer: C. 4R
R = ρL/A: doubling L doubles R and halving A doubles it again, giving 4R.
An AdmitMe practice question, written for the JAMB syllabus. Not an official past question.