1.1. This question is about an investigation into how the terminal potential difference (pd) $V$ across a battery varies with the current $I$ (required practical activity 6).

Figure 8 shows a partially completed circuit diagram for this investigation.

Figure 8

Complete Figure 8 to show how an ammeter and a voltmeter should be connected to measure $I$ and $V$.

1.2. The student uses a multimeter to measure $I$ and $V$.

Figure 9 shows the multimeter set to the 200 mA d.c. current range.

Figure 9

What is the reading on the multimeter?

1.3. Figure 10 shows how the multimeter displays the value of $V$ when set to two different d.c. voltage ranges.

Figure 10

Explain whether the 2000 mV range or the 20 V range should be used to measure $V$.

1.4. Explain why the switch should be opened between readings.

1.5. Describe the procedure the student should use to obtain a set of readings of $I$ and $V$.

1.6. Figure 11 shows a graph of the experimental data.

Figure 11

Determine from Figure 11:

• the emf $\epsilon$ of the battery

• the internal resistance $r$ of the battery.

1.7. Determine the percentage uncertainty in $r$ using the multimeter readings from Figure 9 and Figure 10 and the value of $ϵ$ from (f).

The uncertainty in $ϵ$ is negligible.

1.8. The battery is made up of two identical cells. The student removes one of the cells from the circuit in Figure 8 and repeats the experiment.

Compare the graph produced for this second investigation with the graph shown in Figure 11.