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WAEC Physics 2024 Objective — Question 40

Question 40 of 50 from the West African Examinations Council (WAEC) Physics 2024 Objective paper, with the correct answer and a full explanation.

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40. Four pieces of constantan wire, marked E, F, G and H, each of length 1.0m, arc at the same temperature. Their respective diameters are 1mm, 2mm, 6mm and 10mm. Which wire has the highest resistance?

  • A. ECorrect
  • B. G
  • C. D
  • D. H

Explanation

From R=(rho x l)/A, we can easily infer that the resistance (R) of a wire increases as cross-sectional area decreases. Since cross-sectional area is large for wires with large diameter and small for those with small diameter, it follows that a wire with a small diameter will have a high resistance -- wire E.

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