question_answer

A current\[i\]ampere flows along the inner conductor of a coaxial cable and returns along the outer conductor of the cable, then the magnetic induction at any point outside the conductor at a distance r metre from the axis is

A) \[\infty \]

B)  Zero

C)  \[\frac{{{\mu }_{0}}}{4\pi }\frac{2i}{r}\]

D)  \[\frac{{{\mu }_{0}}}{4\pi }\frac{2\pi i}{r}\]

Correct Answer: B

Solution :

 The described condition can be shown as The magnetic field at P due to inner and outer conductors are equal and opposite. Hence, the net magnetic field at P will be zero.