Question

The magnetic field between the plates of a capacitor where $r > R$ is given by (where $r$ is the distance from the axis of plates and $R$ is the radius of each plate of capacitor)

• A. $\frac{\mu_{0} i_{D}}{2 \pi R^{2}}$
• B. $\frac{\mu_{0} i_{D}}{2 \pi R}$
• C. $\frac{\mu_{0} i_{D}}{2 \pi r}$
• D. zero

Answer 1

Answer: (C)

Using Ampere circuit law,
$\int B \cdot d l=\mu_{0} i_{D}$
or $B \times 2 \pi r=\alpha_{0} i_{D}$
or $B=\mu_{0} i_{D} / 2 \pi r$