An electron falling freely under the influence of gravity enters a uniform magnetic field directed towards south. The electron is initially deflected towards

Two long straight parallel wires $A$ and $B$ separated by 5 m carry currents 2 A and 6 A respectively in the same direction. The resultant magnetic field due to the two wires at a point of 2 m distance from the wire $A$ in between the two wires is

A long straight rod of diameter 4 mm carries a steady current $i$. The current is uniformly distributed across its cross-section. The ratio of the magnetic fields at distances 1 mm and 4 mm from the axis of the rod is

A straight wire of length 20 cm carrying a current of $\frac{3 .}{\pi^2} \mathrm{~A}$ is bent in the form of a circle. The magnetic field at the centre of the circle is