(a) Six lead-acid type of secondary cells each of emf $2.0\mathrm{V}$ and internal resistance $0.015\Omega$ are joined in series to provide a supply to a resistance of $8.5\Omega$ What are the current drawn from the supply and its terminal voltage? (b) A secondary cell after long use has an emf of $1.9\mathrm{V}$ and a large internal resistance of $380\Omega$. What maximum current can be drawn from the cell? Could the cell drive the starting motor of a car? 3 Two wires of equal length, one of aluminium and the other of copper have the same resistance. Which of the two wires is lighter? Hence explain why aluminium wires are preferred for overhead power cables.