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9 (a) Which of these symbols is used to represent a thermistor in an electrical circuit? A B C D (b) A student investigates how the current in a lamp changes with the potential difference across the lamp - Edexcel - GCSE Physics - Question 9 - 2019 - Paper 1
Question 9
9 (a) Which of these symbols is used to represent a thermistor in an electrical circuit? A B C D (b) A student investigates how the current in a lamp chan... show full transcript
Worked Solution & Example Answer:9 (a) Which of these symbols is used to represent a thermistor in an electrical circuit? A B C D (b) A student investigates how the current in a lamp changes with the potential difference across the lamp - Edexcel - GCSE Physics - Question 9 - 2019 - Paper 1
Step 1
Calculate the value of resistance that is missing from the table.
Answer
To find the missing resistance value, we need to apply Ohm's Law, which states that resistance (R) is calculated by the formula:
For the potential difference of 4.0 V, and current 0.22 A, we get:
Thus, the missing resistance is approximately 18.2 Ω.
Step 2
Comment on the student's conclusion.
Answer
The student's conclusion that "The resistance of the lamp is directly proportional to the potential difference" is supported by the observed data in Figure 17. As the potential difference increases from 1.0 V to 6.0 V, the current also increases, suggesting a linear relationship. However, the resistance values do not remain constant; at 4.0 V, the resistance calculation suggests this may not hold for all values. Therefore, while there is a general trend indicating proportionality, the resistance itself appears to be variable.
Step 3
Explain, in terms of the movement of charged particles, how energy is transferred from the battery, through the lamp, to the surroundings.
Answer
When the circuit is completed, charged particles (electrons) move from the negative terminal of the battery through the circuit. As the electrons flow through the filament lamp, they collide with the atoms in the lamp's material. This collision causes the atoms to vibrate, producing heat energy, which then converts to light energy. This process continues until the electrons reach the positive terminal of the battery, completing the circuit. The energy transfer from electrical to thermal and then to light energy illustrates how energy is used from the battery in practical applications.