OR (b) (i) Answer the following giving reason : (I) The electron drift speed is estimated to be only a few $\text{mm/s}$ for currents in the range of a few amperes. How, then, is the current established almost the instant a circuit is closed ? (II) A low voltage supply from which one needs high currents must have very low internal resistance. Why ? (III) The assertion that $V = \text{IR}$ is a statement of Ohm's law is not true. Why ?