Question

A toroid wound with $100$ turns/m of wire carries a current of $3A$. The core of toroid is made of iron having relative magnetic permeability of ${\mu }_r=5000$ under given conditions. The magnetic field inside the iron is ____
(Take ${\mu }_o=4\pi \times {10}^{-7}Tm{A}^{-1}$)

• A. $0.15T$
• B. $1.5\times {10}^{-2}T$
• C. $0.47T$
• D. $1.88T$

Answer 1

The correct option is D $1.88T$

For a toroid, the magnetic field inside the iron is$=B={\mu }_{r}nI$

$\therefore B=5000\times 100\times 3\times 4\pi \times {10}^{-7}=1.88T$