The voltage (potential difference) across a length of wire is 1.5 V - Edexcel - GCSE Physics - Question 8 - 2023 - Paper 2

The voltmeter should be connected in parallel with the iron wire to measure the voltage across it, while the ammeter should be connected in series with the iron wire to measure the current. The diagram should show the connections appropriately, ensuring that the symbols for both devices are included.

A straight line of best fit should be drawn on Figure 21, ideally passing through the center of the data points to represent the relationship observed in the experiment.

By referencing Figure 21, find the corresponding resistance value for a 100 cm length of iron wire. Read the value at the 100 cm mark and note that it may be approximately in the range of the measured values represented in the graph.

Using the equation:

$V = I × R$

We can rearrange this to find resistance:

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

Substituting in the known values:

• Voltage, V = 1.56 V
• Current, I = 0.45 A

Calculating gives:

$R = \frac{1.56}{0.45} = 3.47 ext{ Ω}$

Therefore, the resistance of the piece of wire is approximately 3.47 Ω.