A current, $I=5.0 \mathrm{A}$ flows along a thin wire shaped as shown in the figure. The radius of a curved part of the wire is equal to $R=120 \mathrm{mm}$, the angle, $2\mathit{\text{φ}}=90°$. Find the magnetic induction of the field at the point $O$ (permeability of vacuum, ${\mu }_0=1.257\times {10}^{-6} \mathrm{H} {\mathrm{m}}^{-1}$).

Find the magnetic induction of the field at the point $O$ of a loop, with current $I$, whose shape is illustrated.
(a) 

The radii $a$ and $b$, as well as the angle $\phi$ are known.
(b) 

the radius $a$ and the side $b$ are known.

A current $I$ flows in a long straight wire with cross-section having the form of a thin half-ring of radius $R$. Find the induction of the magnetic field at the point $O$. 

Find the magnetic induction of the field at the point $O$ if a current-carrying wire has the shape shown in figure. The radius of the curved part of the wire is $R$, the linear parts are assumed to be very long.

Find the magnetic induction at the point $O$, if the wire carrying a current $I=8.0 \mathrm{A}$ has the shape shown in the figure.

The radius of the curved part of the wire is $R=100 \mathrm{mm}$, the linear parts of the wire are very long

Find the magnitude and direction of the magnetic induction of vector $\overrightarrow{\mathit{B}}$, 

$\left(a\right)$ of an infinite plane carrying a current of linear density $\hat{\mathrm{i}}$, the vector $\hat{\mathrm{i}}$ is the same at all points of the plane, 
$\left(b\right)$ of two parallel infinite planes carrying currents of linear densities $\hat{\mathrm{i}}$ and $-\hat{\mathrm{i}}$, the vectors $\hat{\mathrm{i}}$ and $-\hat{\mathrm{i}}$ are constant at all points of the corresponding planes.