Answer
2.3 mA
Work Step by Step
V= 0.70 V
l= 100 m
Resistivity of gold $\rho=2.4\times10^{-8} Ωm$
$r=0.05\times10^{-3}m$
A= $\pi r^{2}=\pi (0.05\times10^{-3}m)^{2}$
Current I= $\frac{V}{R}=\frac{V}{\rho \frac{l}{A}}$ $= \frac{VA}{\rho l}=\frac{0.70 V\times\pi (0.05\times10^{-3}m)^{2}}{2.4\times10^{-8} Ωm\times100m}= 2.3\times10^{-3}A$= 2.3 mA
