What cross-sectional area do you need to take an iron wire 10 m long so that its resistance
| July 28, 2021 | education
What cross-sectional area do you need to take an iron wire 10 m long so that its resistance is the same as that of a nickel wire with a cross-sectional area of 0.2 mm2 and a length of 1 m.
Lzh = 10 m.
ρzh = 0.1 Ohm * mm2 / m.
Sn = 0.2 mm2.
Ln = 1 m.
ρн = 0.4 Ohm * mm2 / m.
Rzh = Rn.
Szh -?
The resistance R of a uniform cylindrical conductor of length L and cross-sectional area S is determined by the formula: R = ρ * L / S, where ρ is the resistivity of the material from which the conductor is made.
Rzh = ρzh * Lzh / Szh.
Rn = ρn * Ln / Sn.
ρl * Ll / Sl = ρn * Ln / Sn.
Sl = ρl * Ll * Sn / ρn * Ln.
Szh = 0.1 Ohm * mm2 / m * 10 m * 0.2 mm2 / 0.4 Ohm * mm2 / m * 1 m = 0.5 mm2.
Answer: the iron conductor must have a cross-sectional area Szh = 0.5 mm2.
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