A Levels Physics (9702)•9702/13/O/N/18

Explanation
Resistance Formula for Conductors Steps:
- Use R = ρL/A, with ρ = 2.30 × 10^{-8} Ω·m, L = 2.50 × 10^{-2} m, A = 6.25 × 10^{-7} m².
- Compute ρL = (2.30 × 10^{-8}) × (2.50 × 10^{-2}) = 5.75 × 10^{-10}.
- Divide by A: 5.75 × 10^{-10} / 6.25 × 10^{-7} = 9.2 × 10^{-4} Ω.
- Result matches option C.
Why C is correct:
- It equals the value from R = ρL/A, the standard formula for wire resistance.
Why the others are wrong:
- A: Overestimates by factor of ~60, likely from inverting A and L.
- B: Underestimates by factor of ~4, possibly from miscalculating ρL product.
- D: Too small by factor of ~10, perhaps from extra division error.
Final answer: C
Topic: Resistance and resistivity
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