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

$\mathrm{I} - \mathrm{V}$ graphs for two different electrical appliances $P$ and $Q$ are shown in the diagram. If ${\mathrm{R}}_{\mathrm{P}}$ and $R_{\mathrm{Q}}$ be the resistances of the devices, then

In the given circuit, the current through $2 \mathrm{\Omega }$ resistor is