1 (a) Figure 1 shows the results from an experiment where the potential difference (voltage) across a filament lamp was varied - Edexcel - GCSE Physics Combined Science - Question 1 - 2021 - Paper 1
Question 1
1 (a) Figure 1 shows the results from an experiment where the potential difference (voltage) across a filament lamp was varied.
The current and voltage were measure... show full transcript
Worked Solution & Example Answer:1 (a) Figure 1 shows the results from an experiment where the potential difference (voltage) across a filament lamp was varied - Edexcel - GCSE Physics Combined Science - Question 1 - 2021 - Paper 1
Step 1
Describe the relationship between the current and the voltage as shown in the graph in Figure 1.
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Answer
The graph indicates a positive correlation between the current and the voltage: as the potential difference (voltage) increases, the current also increases. However, this increase happens at a decreasing rate, indicating that the graph is non-linear and not directly proportional.
Step 2
Use the values of the voltage and current at point P and at point Q on the graph in Figure 1 to complete the table in Figure 2.
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Answer
For point P, the voltage is 2.0 V and the current is 30 mA. For point Q, the voltage is 4.0 V and the current is 55 mA.
Step 3
Calculate the resistance of the filament lamp when the voltage is 4.5V and the current is 51 mA.
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Answer
Using the formula for resistance, R = V / I, we convert the current from mA to A: 51 mA = 0.051 A. Therefore,
R=0.051A4.5V≈88.24Ω
Step 4
Explain why the resistance of the filament lamp changes as the voltage across it increases.
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Answer
The resistance of the filament lamp increases with voltage due to the heating effect in the filament as current flows. As the filament heats up, its atomic structure becomes more vibrational, leading to increased collisions between electrons and the atoms, which in turn raises the resistance.
