The resistance of 90m of copper wire equals 2 ohms. Determine the final cross-sectional area of the wire.
| April 3, 2021 | education
Task data: l (length of a given copper wire) = 90 m; R (required wire resistance) = 2 ohms.
Reference values: ρm (specific electrical resistance of copper) = 0.017 Ohm * mm2 / m.
We express the required cross-sectional area of a given copper wire from the formula: R = ρm * l / S, whence S = ρm * l / R.
Calculation: S = 0.017 * 90/2 = 0.765 mm2.
Answer: The cross-sectional area of a given copper wire should be 0.765 mm2.
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