A current I flows through an infinitely long, straight copper walled pipe. Then:
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → The magnetic field at any point inside the pipe is zero
Current inside conductor = 0A
$\phi\vec B.\vec{dl}=μ_0I$
$B2\pi r=μ_0(0)$
$B=0$