Question

Eighteen-gauge wire has a diameter of 1.024 mm. Calculate the resistance of 19 m of 18 gauge lead wire at 20°C.

Answer 1

The answer is 5.075 ohms

Answer 2

resistivity at 20℃ is
ρ=22•10⁻⁸ Ohm•m

R= ρL/A= 4ρL/πD²=
=2•22•10⁻⁸•19/ π(1.024•10⁻³)²=
=5.076 Ohms

Answer 3

5.1 (as the number of significant figures should be 2).