Ten million electrons pass from point $P$ to point $Q$ in one micro second. The current and its direction is

The following figures show four situations, in which positive and negative charges move horizontally through a region and give the rate at which each charge moves. Rank the situations according to the effective current through the region greatest first.

A thin metallic spherical shell carries a charge $Q$ on it. A point charge $q$ is placed at the centre of the shell and another charge $q_1$ is placed outside it, as shown in figure. All the three charges are positive.

The force on the charge at the centre is 

$I-V$ characteristic of a copper wire of length $L$ and area of cross-section $A$ is shown in the figure. The slope of the curve becomes