alleryA copper wire of length 1 m and cross-section 1 mm² has resistivity 1.7 × 10⁻⁸ Ω·m. Its resistance is:
A1.7 × 10⁻² Ω
B1.7 × 10⁻⁵ Ω
C1.7 × 10⁻⁸ Ω
D17 Ω
Answer & Solution
Correct answer: A. 1.7 × 10⁻² Ω
We have R = ρl/A.
That is R = (1.7 × 10⁻⁸) × 1 / (1 × 10⁻⁶).
That is R = 1.7 × 10⁻² Ω.
So R = 0.017 Ω.
(Convert mm² to m²: 1 mm² = 10⁻⁶ m².)
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