Q 12-04-153JEE MainJEE Main 2022 (26 Jul, Shift 1)Easy
$B_X$ and $B_Y$ are the magnetic fields at the centres of two coils $X$ and $Y$ respectively, each carrying equal current. If coil $X$ has $200$ turns and $20\ \text{cm}$ radius and coil $Y$ has $400$ turns and $20\ \text{cm}$ radius, the ratio of $B_X$ and $B_Y$ is
Answer: (B) $1 : 2$
$B = \dfrac{\mu_0NI}{2r}$; with equal $I$ and $r$, $B\propto N$: $B_X : B_Y = 200 : 400 = 1 : 2$.
Solution by Sreeraj P, M.Sc Physics