Question

Calculate the electric field in a copper wire of cross-sectional area 2.0 mm2 carrying a current of 1 A.
The resistivity of copper = 1.7 × 10–8 Ω m

Answer 1

Given:

Area of cross-section, A = 2 × 10–6 m2

Current through the wire, i = 1 A

Resistivity of copper, ρ = 1.7 × 10–8 Ωm

Resistance of a wire,

R=ρlA

Also from Ohm's Law, voltage across a wire,

V=iR=iρlA

The electric field of the wire,

E=Vl⇒E=iρlAl=iρA⇒E=1×1.7×10−82×10−6⇒E=8.5 V/m