Q 12-05-026JEE MainJEE Main 2026 (4 Apr, Shift 2)Easy
A solenoid has a core made of material with relative permeability $400$. The magnetic field produced in the interior of solenoid is $1.0$ T. The magnetic intensity in SI units is $\alpha \times 10^5$. The value of $\alpha$ is ______.
(Free space permeability $\mu_0 = 4\pi \times 10^{-7}$ SI units.)
Answer: (B) $\dfrac{1}{16\pi}$
$H = \dfrac{B}{\mu_0\mu_r} = \dfrac{1.0}{4\pi \times 10^{-7} \times 400} = \dfrac{10^4}{16\pi \times 10^{-2}}\cdot 10^{-2}$
$= \dfrac{1}{1.6\pi \times 10^{-4}} = \dfrac{1}{16\pi} \times 10^5$ A/m.
Solution by Sreeraj P, M.Sc Physics