Question

A copper wire has a diameter of 1.02mm,cross sectional area 8.2×10^-7 and resistivity 1.72×10^-8ohm meter.It caries a current 1.67A.Find the electric field magnitude in the wire and the potential difference between two points in the wire 50m apart.

Answer 1

Electric field:

$E=\frac{\rho I}{S}=\frac{1.72×10^{-8}*1.67}{8.2×10^{-7}}=35 \frac{mV}{m}$

Potential difference:

$U=\frac{\rho*L}{S}I=\frac{1.72×10^{-8}*50*1.67}{8.2*10^{-7}}=1.75$ V