A student investigated how the current in a filament lamp varied with the potential difference across the filament lamp - AQA - GCSE Physics - Question 8 - 2020 - Paper 1

Draw a smooth curve that passes through the negative coordinate values of the graph, ensuring that the line does not become horizontal. This line should demonstrate the relationship between negative current and negative potential difference, showing that, as one decreases, the other does as well.

The equation that links current (I), potential difference (V), and resistance (R) is given by: $V = I imes R$

To find the resistance of the filament lamp when the potential difference is 1.0 V, use the current value obtained from Figure 12. Assuming the current at 1.0 V is 0.08 A, apply the formula:
$R = \frac{V}{I} = \frac{1.0 ext{ V}}{0.08 ext{ A}} = 12.5 \Omega$
Thus, the resistance of the filament lamp is 12.5 Ω.

A zero error in an ammeter indicates that the ammeter gives a reading when no current is passing through the circuit. This means that the ammeter's baseline reading is offset from zero, necessitating a correction to ensure that measurements of current are accurate.