Question

A toroid with thick windings of $N$ turns has inner and outer radii $R_{1}$ and $R_{2}$ respectively. If it carries certain steady current I, the variation of the magnetic field due to the toroid with radial distance is correctly graphed in

• A.
• B.
• C.
• D.

Answer 1

Answer: (D)

Answer 2

$B =\mu_{0} nI$ where $n =\frac{ N }{2 \pi r }$ $B=\frac{\mu_{0} N I}{2 \pi\left(\frac{R_{1}+R_{2}}{2}\right)}$ $B=\frac{\mu_{0} N I}{\pi\left(R_{1}+R_{2}\right)}$