Question

A current of $1/4\pi$ ampere is flowing through a toroid. It has $1000$ number of turn per meter then value of magnetic field (in $Wb/m^2$) along its axis is:

• A. ${10}^{-3}$
• B. ${10}^{-4}$
• C. ${10}^{-2}$
• D. ${10}^{-7}$

Answer 1

Answer: (A)

${10}^{-3}$

Here, we know that Magnetic field outside the toroid is zero.

Also, magnetic field at the center of toroid is also zero.

Therefore, $B={\mu }_{0}nI$

=$4\pi \ast {10}^{-7}\ast 1000\ast \frac{1}{4\pi }$

=${10}^{-3}W/m^2$