A semicircular arc of radius $20 \mathrm{cm}$ carries a current of $10 A$. Calculate the magnitude of the magnetic field at the centre of the arc.

Two identical circular wires $P$ and $Q$ each of radius $R$ and carrying current $‘I’$ are kept in perpendicular planes such that they have a common centre as shown in figure. Find the magnitude and direction of the net magnetic field at the common centre of the two coils.

Two identical loops $P$ and $Q$ each of radius $5 \mathrm{cm}$ are lying in perpendicular planes such that they have a common centre as shown in the figure. Find the magnitude and direction of the net magnetic field at the common centre of the two coils, if the carry currents equal to $3 A$ and $4 A$ respectively.

A thick straight copper wire, carrying a current of $10 A$ is bent into a semicircular arc of radius $7.0 \mathrm{cm}$ as shown in Figure (a) (i) State the direction and calculate the magnitude of magnetic field at the centre of arc. (ii) How would your answer change if the same wire were bent into a semicircular arc of the same radius but in opposite way as shown in Figure (b)?

A long wire is bent, as shown in Figure. Find the magnitude and direction of the magnetic field at the centre $O$ of the circular part, if a current $I$ is passed through the wire.

Figure shows two semicircular loops of radii $R_1$ and $R_2$ carrying current $I$. Find the magnitude and direction of the magnetic field at the common centre $O$.

A circular segment of radius $10 \mathrm{cm}$ subtends an angle of $60°$ at its centre. A current of $9 A$ is flowing through it. Find the magnitude and direction of the magnetic field produced at the centre.