Question

A copper wire of cross-sectional area $2.0\, mm ^{2}$ resistivity $=1.7 \times 10^{-8} \Omega$, carries a current of $1 A$. The electric field in the copper wire is

• A. $8.5 \times 10^{-5} Vm ^{-1}$
• B. $8.5 \times 10^{-4} Vm ^{-1}$
• C. $8.5 \times 10^{-3} Vm ^{-1}$
• D. $8.5 \times 10^{-2} Vm ^{-1}$

Answer 1

Answer: (C)

$E=\frac{V}{l}=\frac{i R}{l}=\frac{i \rho l}{A l}=\frac{i \rho}{A}=\frac{1 \times 1.7 \times 10^{-8}}{2 \times 10^{-6}} $
$=8.5 \times 10^{-3} Vm ^{-1}$