Determine the resistance of a 100 ft length of copper wire with a diameter of 20 mils. Assume resistivity ρ = 10.37 CM-Ω/ft

Question

Question

This question was previously asked in

MPPGCL JE Electrical 19 March 2019 Shift 2 Official Paper

Answer 1

Concept

The resistance of a wire is given by:

\(R=ρ{l\over A}\)

where, R = Resistance

ρ = Resistivity

l = Mean length per turn

A = Cross-sectional area

The area in circular mils is given by:

Area = d2 , where d is diameter

Calculation

Given, d = 20 mils

Area = 400 cm

\(R=10.37\times {100\over 400}\)

R = 2.59 Ω