Photo AI
A student investigated how current varies with potential difference for two different lamps - AQA - GCSE Physics - Question 8 - 2018 - Paper 1
Question 8
A student investigated how current varies with potential difference for two different lamps. Her results are shown in Figure 10. **Figure 10** Complete the circuit... show full transcript
Worked Solution & Example Answer:A student investigated how current varies with potential difference for two different lamps - AQA - GCSE Physics - Question 8 - 2018 - Paper 1
Step 1
Complete the circuit diagram for the circuit that the student could have used to obtain the results shown in Figure 10.
Answer
The circuit diagram should include a:
- Battery in series with the lamps (Lamp A and Lamp B), a
- Voltmeter connected in parallel to the lamp to measure potential difference, and an
- Ammeter in series to measure the current. A variable resistor could also be included to adjust the current.
Step 2
Which lamp will be brighter at any potential difference? Explain your answer. Use Figure 10 to aid your explanation.
Answer
Lamp A will be brighter at any potential difference because it has a higher current than Lamp B at the same potential difference, as shown in Figure 10. A higher current correlates to a higher energy output, leading to increased brightness.
Step 3
Lamp B has the higher resistance at any potential difference. Explain how Figure 10 shows this.
Answer
Lamp B demonstrates a lower current than Lamp A for the same potential difference, indicating a higher resistance. This can be expressed using Ohm's law, where resistance (R) is calculated as voltage (V) divided by current (I): . The lower gradient of the line representing Lamp B confirms its higher resistance.
Step 4
Both lamps behave like ohmic conductors through a range of values of potential difference. Use Figure 10 to determine the range for these lamps. Explain your answer.
Answer
Both lamps behave like ohmic conductors from approximately 0 V to 2 V as they have linear characteristics in this region, indicating that current is directly proportional to potential difference. Beyond this range, the graphs begin to deviate from linearity, indicating a non-ohmic behavior.