Question

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. $\frac { \mu _ { 0 } } { 4 \pi } \frac { 2 i } { r }$
• D. $\frac { \mu _ { 0 } } { 4 \pi } \frac { 2 \pi i } { r }$

Answer 1

Answer: (B)

Zero

Answer 2

The respective figure is shown below

Magnetic field at P due to inner and outer conductors are equal and opposite. Hence net magnetic field at P will be zero.