University Physics II · Magnetic forces and sources
Magnetic field in and around a coaxial cable
Problem
An ideal coaxial cable has a solid inner conductor of radius $a$ carrying total current $+I$ uniformly and a thin outer cylindrical shell of radius $b>a$ carrying return current $-I$. Derive $B(r)$ in the regions $r<a$, $a<r<b$, and $r>b$. State the field direction.
Hint
For $r<a$, the enclosed fraction of uniform inner current is $r^2/a^2$.
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