(a)[1]
State Kirchhoff’s first law about current at a junction.
(b(i).1)[1]
A potentiometer is connected to a battery of electromotive force (e.m.f.) $9.6\,\text{V}$ and negligible internal resistance, as shown in Fig. 7.1. The potentiometer has a maximum resistance of $800\,\Omega$. A resistor $R$ with resistance $400\,\Omega$ is connected between the slider and end $X$ of the potentiometer. State the potential difference across resistor $R$ when the slider is placed at end $X$ of the potentiometer.
(b(i).2)[1]
State the potential difference across resistor $R$ when the slider is placed at end $Y$ of the potentiometer.
(b(ii))[3]
Calculate the potential difference across resistor $R$ when the slider is halfway between $X$ and $Y$.