Cross-section 71254

The steel conductors of the long-distance power line have a cross-section of 5 cm². Calculate the resistance of a steel wire with a length of 2 km if the resistivity of the steel is 13 * 10-8 Ω · m.

Correct answer:

R =  0.52 Ω

Step-by-step explanation:

$$\begin{gathered} S=5{\text{cm}}^2\to {\text{m}}^2=5:10000{\text{m}}^2=0.0005{\text{m}}^2 \\ l=2\text{km}\to \text{m}=2\cdot 1000\text{m}=2000\text{m} \\ \rho =13\cdot 10^{-8}\doteq 1.3\cdot 10^{-7}\Omega \\ R=\rho \cdot \frac{l}{S}=1.3\cdot 10^{-7}\cdot \frac{2000}{0.0005}=\frac{13}{25}\Omega =0.52\Omega \end{gathered}$$

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