# What is the height of a copper wire with a cross-sectional area of 0.1 mm2 if, at a voltage of 1.7 watts

**What is the height of a copper wire with a cross-sectional area of 0.1 mm2 if, at a voltage of 1.7 watts, the current through it is exactly 1 ampere.**

S = 0.1mm ^ 2.

U = 1.7 V.

I = 1 A.

ρ = 0.017 Ohm * mm ^ 2 / m.

l -?

The resistance R of a cylindrical homogeneous conductor is determined 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 of the conductor.

l = R * S / ρ.

We express the resistance of the conductor R from Ohm’s law for a section of the circuit: R = U / I.

The formula for determining the length of the conductor will take the form: l = U * S / ρ * I.

l = 1.7 V * 0.1 mm ^ 2 / 0.017 Ohm * mm ^ 2 / m * 1 A = 10 m.

Answer: a copper conductor has a length of l = 10 m.