The current density in a cylindrical wire of radius $r=4.0 \,mm$ is $1.0 \times 10^{6} \,A / m ^{2}$. The current through the outer portion of the wire between radial distances $r / 2$ and $r$ is $x \pi A$; where $x$ is ..........
JEE MAIN 2022, Diffcult
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