Question

Two coaxial hollow conducting cylinder shells carry equal and opposite currents. Magnetic field due to a point outside both the shells is $\overline{B}$ due to one shell and ${\overline{B}}_2$ due two the other shell then:

• A. ${\overline{B}}_1={\overline{B}}_2$
• B. ${\overline{B}}_1=-{\overline{B}}_2$
• C. Depend on radius of cylinders
• D. Depend on distance from conductor

Answer 1

The correct option is D Depend on distance from conductor

The follow cylinder act like two straight conductors, everything current I in opposite directions, taking a point outside the cylinder, the magnetic field (B) in given by :-

$B=\frac{{\mu }_{0}I}{2\pi r}$

So, B depends on 'r' i.e. distance from the conductor.