State what electric current means.
Define what is meant by electric potential difference.
The way current $I$ varies with potential difference $V$ for component $Y$ and for resistor $R$ is shown in Fig. 6.1.
Use Fig. 6.1 to explain how it is possible to deduce that resistor $R$ has a constant resistance of $20\,\Omega$.
The component $Y$ and resistor $R$ in (b) are connected in parallel, as illustrated in Fig. 6.2. A battery with e.m.f. $E$ and negligible internal resistance is attached across the parallel pair. Use data from Fig. 6.1 to determine (i) the current in the battery when $E = 6.0\,\text{V}$, (ii) the total resistance of the circuit when $E = 8.0\,\text{V}$.
Determine the current in the battery when the e.m.f. is $E = 6.0\,\text{V}$.
Determine the total resistance of the circuit when the e.m.f. is $8.0\,\text{V}$.
The circuit shown in Fig. 6.2 is now rearranged as in Fig. 6.3. The current in the circuit is $0.20\,\text{A}$.
Use Fig. 6.1 to find the e.m.f. $E$ of the battery.
Calculate the total power dissipated in component $Y$ together with resistor $R$.