The magnetic induction at the centre $O$ in the figure shown is
$\frac{{{\mu _0}i}}{4}\left( {\frac{1}{{{R_1}}} - \frac{1}{{{R_2}}}} \right)$
$\frac{{{\mu _0}i}}{4}\left( {\frac{1}{{{R_1}}} + \frac{1}{{{R_2}}}} \right)$
$\frac{{{\mu _0}i}}{4}({R_1} - {R_2})$
$\frac{{{\mu _0}i}}{4}({R_1} + {R_2})$
Find the magnetic field at $P$ due to the arrangement shown
$B _{ X }$ and $B _{ Y }$ are the magnetic field at the centre of two coils of two coils $X$ and $Y$ respectively, each carrying equal current. If coil $X$ has $200$ turns and $20 cm$ radius and coil $Y$ has $400$ turns and $20 cm$ radius, the ratio of $B _{ X }$ and $B _{ Y }$ is
In a region of space, a uniform magnetic field $B$ exists in the $y-$direction.Aproton is fired from the origin, with its initial velocity $v$ making a small angle $\alpha$ with the $y-$ direction in the $yz$ plane. In the subsequent motion of the proton,
An electron moves in a circular orbit with a uniform speed $v$. It produces a magnetic field $B$ at the centre of the circle. The radius of the circle is proportional to
Two concentric coplanar circular loops of radii ${r_1}$ and ${r_2}$ carry currents of respectively ${i_1}$ and ${i_2}$ in opposite directions (one clockwise and the other anticlockwise.) The magnetic induction at the centre of the loops is half that due to ${i_1}$ alone at the centre. If ${r_2} = 2{r_1}.$ the value of ${I_2}/{I_1}$ is....