Figure 10 shows two different types of the same circuit component - Edexcel - GCSE Physics Combined Science - Question 5 - 2021 - Paper 1
Question 5
Figure 10 shows two different types of the same circuit component.
What is the name of this circuit component?
A diode
B light dependent resistor
C thermistor
D... show full transcript
Worked Solution & Example Answer:Figure 10 shows two different types of the same circuit component - Edexcel - GCSE Physics Combined Science - Question 5 - 2021 - Paper 1
Step 1
What is the name of this circuit component?
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Answer
The circuit component shown in Figure 10 is a thermistor. Thermistors are temperature-dependent resistors and are typically used in temperature sensing applications.
Step 2
Which row in the table describes the way that ammeters and voltmeters should be connected with a component in a circuit?
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Answer
The correct way to connect an ammeter and voltmeter is as follows:
Row B - ammeter in parallel and voltmeter in series for accurate measurements across a component.
Step 3
(i) Describe the relationship between the current and the voltage as shown in the graph in Figure 11.
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Answer
The graph in Figure 11 depicts a nonlinear relationship between current and voltage. As the voltage increases, the current also increases but not at a constant rate. This suggests that the filament lamp exhibits resistance that changes with temperature, leading to a decrease in current increase efficiency at higher voltages.
Step 4
(ii) Use the values of the voltage and current at point P and at point Q on the graph in Figure 11 to complete the table in Figure 12.
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Answer
The values for the table are:
Point P: Voltage = 2.0 V, Current = 20 mA
Point Q: Voltage = 4.5 V, Current = 50 mA
Step 5
(iii) Calculate the resistance of the filament lamp when the voltage is 4.5 V and the current is 51 mA.
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Answer
Using the formula for resistance:
R=IV
We substitute the given values:
R=51×10−34.5
Calculating this gives us:
R=88.24Ω
Thus, the resistance of the filament lamp is approximately 88.2 Ω.
Step 6
(iv) 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 changes with voltage because, as the voltage increases, the temperature of the filament also rises due to increased power dissipation. Since the filament is typically made of tungsten, its resistance increases significantly as it heats up, which is a characteristic behavior of metallic conductors.
