A long infinite current-carrying wire is bent in the shape as shown in the figure. The magnetic induction at a point $O$ is,

All the straight wires, in the diagram, are very long. It is also given that, both $AB$ and $CD$ are arcs of the same circle and both subtend right angles at the Centre $O$. The magnetic field at $O$ is

In the given figure, the magnetic induction at the Centre point $O$ of a semicircle is

Magnetic field at the Centre $O$, of an equilateral triangle of side $2 \mathrm{cm}$, with current flowing, as shown below, is (Resistance of the part $ABC$ is $2 \mathrm{\Omega }$ and resistance of the part $ADC$ is $4 \mathrm{\Omega }$.)

A current, $I=2.5 \mathrm{A}$, flows along a circle, having equation $x^2+y^2=9$ (where, $x$ and $y$ are in $\mathrm{cm}$), as shown. The magnetic field at a point $(0, 0, 4) \mathrm{cm}$ is given by

A long wire is bent, as shown in the below figure. It carries current  $I=10 \mathrm{A}$. If the radius of the semicircular portion is $1 \mathrm{m}$, the magnetic induction (in $\mu T$) at the centre $c$ is 

Equal current of $4 \mathrm{A}$ is flowing in two parallel conductors kept at a distance of $2 \mathrm{m}$ in mutually opposite directions, as shown in the figure. The magnetic conduction (in $\mathrm{\mu T}$) at a point $P$, equidistant from both the conductors at a distance $2 \mathrm{m}$, will be