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16 A student investigated the current-potential difference relationship for a filament bulb - Edexcel - A-Level Physics - Question 16 - 2023 - Paper 2
Question 16
16 A student investigated the current-potential difference relationship for a filament bulb. She set up the circuit as shown. 0-12V power supply The student incre... show full transcript
Worked Solution & Example Answer:16 A student investigated the current-potential difference relationship for a filament bulb - Edexcel - A-Level Physics - Question 16 - 2023 - Paper 2
Step 1
Explain the shape of the graph.
Answer
The graph displays a non-linear relationship between the current (I) and the potential difference (V) across a filament bulb. Initially, as the voltage increases from 0 V, the current also increases. This reflects the filament's behavior as it heats up, allowing more electrons to flow due to increased thermal energy.
As the voltage continues to rise, the rate of increase in current slows down, resulting in a curve that flattens. This behavior can be attributed to two factors: the increasing resistance of the filament due to its temperature and the material properties of the filament itself which limit the current at higher voltages.
Overall, the shape indicates that at lower voltages, the filament behaves nearly like a conductor; however, as temperature rises, it approaches saturation, leading to a reduced rate of current increase.
Step 2
Describe how the student could adapt her method to plot the variation of current with potential difference for the diode in forward bias.
Answer
To adapt the method for examining a diode in forward bias, the student should follow these steps:
- Replace the Bulb with a Diode: The filament bulb should be removed from the circuit and replaced with a diode, ensuring proper orientation to allow current to flow in the forward direction.
- Adjust the Resistor: Introduce an appropriate resistor in series with the diode. This resistor will limit the current to prevent damage to the diode at higher voltages.
- Increment the Voltage: Using the power supply, increase the voltage from 0 V upwards. For each increment, measure the current through the circuit accurately using the ammeter.
By recording the corresponding current values at each voltage setting, she can accurately create a graph that shows the relationship between the current and the potential difference across the diode.