(a)[2]
Using energy changes, describe the electromotive force (e.m.f.) of a battery and the potential difference (p.d.) across a resistor. Describe: - e.m.f. - p.d.
(b(i).1)[1]
The variable resistor $X$, with resistance $R_X$, is adjusted until the voltmeter shows $4.8\,\text{V}$. Calculate the current in resistor $Z$.
(b(i).2)[2]
Calculate the total power supplied by the battery.
(b(i).3)[2]
Calculate the number of conduction electrons that pass through the battery in a time interval of $25\,\text{s}$.
(b(i).4)[2]
Calculate the total resistance of $X$ and $Y$ in parallel.
(b(i).5)[2]
Calculate the resistance $R_X$.
(b(ii))[2]
The resistance $R_X$ is now reduced. State and explain any change in the voltmeter reading.