The shape of the magnetic field lines due to an infinitely long,straight current-carrying conductor is:

An electron revolves in a circle of radius $0.4 \text{ Å}$ with a speed of $10^6 \text{ m/s}$ in a hydrogen atom. The magnetic field produced at the centre of the orbit due to the motion of the electron (in Tesla) is: $\left[\mu_0 = 4\pi \times 10^{-7} \text{ H/m}, q = 1.6 \times 10^{-19} \text{ C}\right]$

Two long straight parallel wires carry currents of $8 \ A$ and $10 \ A$ in opposite directions. If the distance of separation between the wires is $9 \ cm$, then the net magnetic field at a point between the two wires, which is at a perpendicular distance of $4 \ cm$ from the wire carrying $8 \ A$ current is:

The magnetic field at the centre of a circular coil of radius $R$ due to current $i$ flowing through it is $B$. The magnetic field at a point along the axis at a distance $R$ from the centre is

Two identical circular current loops of radius $R$ carrying equal currents $I$ are placed such that their axes are inclined at $45^\circ$ to each other. The distance from the center of each loop to point $P$ is $\sqrt{3}R$. The resultant magnetic field at $P$ is:

In the given figure,find the magnetic field at point $O$.