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

$A$ straight wire of finite length carrying current $I$ subtends an angle of $60^{\circ}$ at point $P$ as shown. The magnetic field at $P$ is

$A$ current of $i$ ampere is flowing through each of the bent wires as shown. Find the magnitude of the magnetic field at $O$.

In an ionised sodium atom,an electron is moving in a circular path of radius $r$ with angular velocity $\omega$. The magnetic induction in $Wb/m^2$ produced at the nucleus will be

$A$ straight conductor of length $32 \,cm$ carries a current of $30 \,A$. Magnetic induction at a point in air at a perpendicular distance of $12 \,cm$ from the mid-point of the conductor is (in $G$)

Two similar coils, which are separated by $2 \ m$, have a radius of $1 \ m$ and $80$ turns, and share a common axis. Calculate the strength of the magnetic field in microtesla at a point midway between them on their common axis when the current is $0.2 \ A$.