Question

A current I flows along the length of an infinitely long, straight, thin walled pipe. Then
(a) the magnetic field at all points inside the pipe is the same, but not zero
(b) the magnetic field is zero only on the axis of the pipe
(c) the magnetic field is different at different points inside the pipe
(d) the magnetic field at any point inside the pipe is zero

Answer 1

(d) Magnetic field is shielded and no current is inside the pipe to apply Ampère’s law. (Compare to electric field inside a hollow sphere).