A metal wire of uniform cross-sectional area $1 {\mathrm{mm}}^2$ has a free electron density of $6\times {10}^{28} {\mathrm{m}}^{-3}$. If the wire is carrying $0.96 \mathrm{A}$ current, what is the drift velocity of the free electrons along the wire? (Charge on electron$=1.6\times {10}^{-19} \mathrm{C}$).

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.

If the cell of emf $5 \mathrm{V}$ shown in the figure, gives a power of $10 \mathrm{W}$, then, find the power consumed by the resistors $2 \mathrm{\Omega }$ and $1 \mathrm{\Omega }$.