What is the current in a steel conductor with a length of 12 m and a cross-section of 4 mm 2

What is the current in a steel conductor with a length of 12 m and a cross-section of 4 mm 2, to which a voltage of 72 mV is applied?

S = 4 mm2.

U = 72 mV = 0.072 V.

ρ = 0.12 Ohm * mm2 / m.

I -?

The current in the conductor I is directly proportional to the voltage U at its ends and is inversely proportional to the resistance of the conductor R: I = U / R.

For a cylindrical homogeneous conductor, the resistance R is expressed by the formula: R = ρ * L / S, where ρ is the resistivity of the conductor, L is the length of the conductor, S is the cross-sectional area of the conductor.

The formula for determining the current strength will take the form: I = U * S / ρ * L.

I = 0.072 V * 4 mm2 / 0.12 Ohm * mm2 / m * 12 m = 0.2 A = 200 mA.

Answer: the current in the steel conductor is I = 200 mA.