(a)[2]
Define what is meant by electromotive force.
(b(i))[3]
Draw a circuit diagram showing the $1.5\text{ V}$ cells arranged to give an e.m.f. of $7.5\text{ V}$, together with the variable resistor and the $30\Omega$ resistor.
(b(ii))[4]
With the axes in Fig. 7.1, plot a graph showing how the current in the circuit changes as the resistance of the variable resistor rises from $0\Omega$ to $150\Omega$. Find and mark the maximum current on the y-axis.