Three cells with electromotive forces (e.m.f.) $E_1$, $E_2$ and $E_3$ are arranged in the circuit shown in Fig. 5.1. The circuit also contains resistors with resistances $R_1$, $R_2$, $R_3$ and $R_4$. The currents in the separate branches are $I_1$, $I_2$ and $I_3$. The cells have negligible internal resistance.
(a)[1]
Use Kirchhoff’s laws to state an equation linking $I_1$, $I_2$ and $I_3$.
(b)[1]
Use Kirchhoff’s laws to state an equation connecting $E_1$, $E_3$, $R_1$, $R_3$, $R_4$, $I_1$ and $I_3$ in loop WXYZW.
(c)[1]
Use Kirchhoff’s laws to state an equation connecting $E_1$, $E_2$, $R_1$, $R_2$, $I_1$ and $I_2$ in loop YZWY.
Worked solution & mark scheme
This 3-mark question has a full step-by-step worked solution and mark scheme. One marking point: “$I_1 + I_2 = I_3$ (or equivalent)” …