Question

A toroid is shown in the figure Find the correct option about the magnetic field at point $\text{A, B}$ and $\text{C}$.

• A. $B_A=B_B$
• B. $B_A=B_B=B_C$
• C. $B_A=B_C$
• D. $B_B=B_C=0$

Answer 1

The correct option is C $B_A=B_C$

Magnetic field produced by toroid inside the core of toroid means at point $\text{B}$ is given by

$B_B=\frac{{\mu }_{0}Ni}{2\pi r}$

But at point $\text{A},i=0$

$\therefore B_A=0$

And we know that outside the toroid, magnetic field is not exist.

$\therefore B_C=0$

So finally we get

$B_A=B_C=0;B_B=\frac{{\mu }_{0}Ni}{2\pi r}$