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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
Question 8
A student investigated how the current in a filament lamp varied with the potential difference across the filament lamp. Figure 11 shows part of the circuit used. ... show full transcript
Worked Solution & Example Answer: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
Step 1
Complete Figure 11 by adding an ammeter and a voltmeter.
Answer
To complete Figure 11, add an ammeter in series with the filament lamp and a voltmeter in parallel with the lamp. Use the following symbols:
- Ammeter: A circle with 'A' inside it, representing the current measuring device.
- Voltmeter: A circle with 'V' inside it, indicating the voltage measuring device.
Step 2
Draw a line on Figure 12 to show the relationship between the negative values of current and potential difference.
Answer
In Figure 12, draw a smooth curve that reflects the relationship between negative current and negative potential difference. Ensure the line passes through significant points, such as (-4.0 V, -0.2 A) or (-6.0 V, -0.23 A), demonstrating how current decreases as potential difference becomes more negative.
Step 3
Write down the equation which links current (I), potential difference (V) and resistance (R).
Answer
The equation that links current (I), potential difference (V), and resistance (R) is given by: This formula indicates that the potential difference across an electrical component is equal to the product of the current flowing through it and its resistance.
Step 4
Determine the resistance of the filament lamp when the potential difference across it is 1.0 V.
Answer
To determine the resistance of the filament lamp when the potential difference is 1.0 V, first find the current reading corresponding to this voltage from Figure 12. Assuming the current (I) is 0.08 A: 1.0 V = 0.08 A × R Solving for R gives: Thus, the resistance of the filament lamp is 12.5 Ω.
Step 5
What is meant by a zero error?
Answer
A zero error occurs when an instrument, such as an ammeter, does not read zero when it should. In the case of the ammeter used by the second student, this implies that the readings may be inaccurate due to the instrument's inability to return to zero when no current is flowing, leading to potential systematic errors in measurement.