A current of i ampere flows along an infinitely long straight thin walled tube. Then the magnetic in

Question

A current of i ampere flows along an infinitely long straight thin walled tube. Then the magnetic induction at any point inside the tube is\

Professor PC Thomas Classes · Answer

The field inside the tube will be zero. Consider a point inside and apply Ampere's circuital theorem $\oint \overline{\mathrm{B}} . \overline{\mathrm{dl}}=\mu_{0} \mathrm{I}$. The current enclosed by the Ampere's circuit is zero. $	herefore \mathrm{B}=0$