Question

The wall of a straight tube of infinite length is thin and radius of tube is $r$. On passing current $i$ through it, the value of magnetic induction inside the tube will be

• A. $\frac{{\mu }_{0}i}{2\pi r}$
• B. $\frac{{\mu }_{0}i}{2r}$
• C. $\frac{2{\mu }_{0}i}{\pi r}$
• D. $zero$

Answer 1

The correct option is D $zero$

Since it is a thin hollow conductor, there will not be any current passing through inside the hollow portion.
Since $i_{enc}=0$, B is zero inside the tube.