• # question_answer (i) State Kirchhoff's rules for an electrical network. (ii) The plot of the variation of potential difference across a combination of three identical cells in series, versus current is as shown below, What is the emf of each cell?

Let emf of each cell = E Let internal resistance of each cell = r, then $V=(E+E+E)-i(r+r+r)=3(E-ir)$ From the graph, when i = 0, V = 6 i.e.        $6=3(E-0)=3E$             $E=6/3\Rightarrow E=2$