WAEC Physics 2021 Theory — Question 35
Question 35 of 35 from the West African Examinations Council (WAEC) Physics 2021 Theory paper, with the correct answer and a full explanation.
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Practical 2(b)(ii). A resistance wire of diameter 0.6 cm has a resistivity of 1.0×10⁻⁶ Ωm. What length of the wire would be needed to make a 4 Ω resistor?
Model answer
R=ρL/A, so L=RA/ρ = R×π d²/(4ρ) = (4×π×(6×10⁻³)²)/(4×1.0×10⁻⁶) ≈ 113.14 m.
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