The magnetic field at a perpendicular distance '$r$' from a long straight wire carrying current '$I$' is '$B$'. The magnetic field at a perpendicular distance '$2r$' from the same wire is:

The figure shows a straight wire of length $l$ carrying current $i$. The magnitude of the magnetic field produced by the current at point $P$ is:

The magnetic field due to a straight conductor of uniform cross-section of radius $a$ and carrying a steady current is represented by

$A$ long wire is bent into a circular coil of one turn and then into a circular coil of smaller radius having $n$ turns. If the same current is passed in both the cases, the ratio of magnetic field produced at the centre for one turn to that of $n$ turns is

Two identical circular wires of radius $20\,cm$ and carrying current $\sqrt{2}\,A$ are placed in perpendicular planes as shown in the figure. The net magnetic field at the centre of the circular wires is $.............\times 10^{-8}\,T$. (Take $\pi=3.14$ )

$A$ circular coil of wire of radius $r$ has $n$ turns and carries a current $I$. The magnetic induction $B$ at a point on the axis of the coil at a distance $\sqrt{3} r$ from its centre is