Figure 10 shows two different types of the same circuit component - Edexcel - GCSE Physics Combined Science - Question 5 - 2021 - Paper 1

Ammeters should be connected in series with the component to measure the current, while voltmeters should be connected in parallel to measure the voltage across the component. Therefore, the correct row is Row D: ammeter in series, voltmeter in parallel.

The graph in Figure 11 shows a non-linear relationship between current and voltage. As the voltage increases, the current also increases but at a decreasing rate after reaching a certain voltage. This indicates that as the filament lamp heats up, its resistance increases, leading to a non-linear increase in current.

At point P, the voltage is 2.5 V and the current is 20 mA. At point Q, the voltage is 4.5 V and the current is 40 mA.

To calculate the resistance, we will use the formula:

$R = \frac{V}{I}$

Substituting the values:

$R = \frac{4.5 \, \text{V}}{51 \, mA} = \frac{4.5}{51 \times 10^{-3}} \approx 88.24 \, \Omega$

Therefore, the resistance is approximately 88.24 Ω.

As the voltage across the filament lamp increases, the temperature of the filament also increases due to the increase in current flowing through it. This heating effect causes the atoms in the filament to vibrate more, leading to an increase in resistance due to more frequent collisions between the charge carriers (electrons) and the vibrating atoms. Thus, the increased temperature results in an increase in resistance, making the relationship between voltage and current non-linear.