Physics - Current Electricity Question with Solution | TestHub

The current density in a cylindrical wire of radius$4 \mathrm{mm}$is$4\times {10}^6 \mathrm{A} {\mathrm{m}}^{-2}$. The current through the outer portion of the wire between radial distances$\frac{R}{2}$and$R$is _____$\pi \mathrm{A}$.