Final answer:
The length of the plain carbon steel wire is approximately 1.073 meters.
Step-by-step explanation:
To find the length of the plain carbon steel wire, we can use the formula for resistance:
R = (ρ * L) / A, where R is resistance, ρ is resistivity, L is length, and A is the cross-sectional area of the wire.
Given that the diameter of the wire is 3 mm, we can calculate the cross-sectional area:
A = π * (d / 2)^2
Substituting the given values into the formula, we have:
20 = (0.6x10^7 * L) / (π * (1.5x10^-3)^2)
Simplifying the equation and solving for L, we find that the length of the wire is approximately 1.073 meters.