Q 12-04-027NEETJEE MainEasy
A toroid has $500$ turns and mean radius $10$ cm, and carries a current of $2$ A. The magnetic field inside its core is
Answer: (D) $2 \times 10^{-3}$ T
By Ampere's law around the circular core: $B \cdot 2\pi r = \mu_0 N I$.
$$B = \frac{\mu_0 N I}{2\pi r} = \frac{2 \times 10^{-7} \times 500 \times 2}{0.1} = 2 \times 10^{-3}\ \text{T}$$
Solution by Sreeraj P, M.Sc Physics