The current in a steel conductor 140 cm long and a cross-sectional area of 0.2

The current in a steel conductor 140 cm long and a cross-sectional area of 0.2 mm2 is 250 mA. What is the voltage at the ends of this conductor?

l = 140 cm = 1.4 m.

S = 0.2mm ^ 2.

I = 250 mA = 0.25 A.

ρ = 0.1 Ohm * mm ^ 2 / m.

U -?

We express the voltage at the ends of the conductor U from Ohm’s law for the section of the circuit: U = I * R, where I is the current in the conductor, R is the resistance of the conductor.

The resistance of a homogeneous cylindrical conductor R is expressed by the formula R = ρ * l / S, where ρ is the resistivity of the material from which the conductor is made, l is the length of the conductor, S is the cross-sectional area.

U = I * ρ * l / S.

U = 0.25 A * 0.1 Ohm * mm ^ 2 / m * 1.4 m / 0.2 mm ^ 2 = 0.175 V.

Answer: the voltage at the ends of the conductor is U = 0.175 V.