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A student investigates how the resistance of a length of nichrome wire changes with temperature - Edexcel - A-Level Physics - Question 11 - 2023 - Paper 1
Question 11
A student investigates how the resistance of a length of nichrome wire changes with temperature. (a) The student takes measurements to determine the resistance of t... show full transcript
Worked Solution & Example Answer:A student investigates how the resistance of a length of nichrome wire changes with temperature - Edexcel - A-Level Physics - Question 11 - 2023 - Paper 1
Step 1
Draw a diagram of the circuit the student could use.
Answer
To create the circuit, the student should connect a power supply in series with a nichrome wire, an ammeter, and a voltmeter. The ammeter should measure the current flowing through the wire, while the voltmeter should measure the voltage across the wire. This arrangement will allow the student to calculate the resistance using Ohm's law, given by the formula:
where is the resistance, is the voltage, and is the current.
Step 2
Describe how the student could determine the temperature of the wire accurately.
Answer
To measure the temperature of the nichrome wire accurately, the student should use a thermometer. The thermometer should be immersed in the water bath containing the coiled wire to ensure it accurately reflects the temperature of the water. The student should ensure the thermometer is allowed to equilibrate with the water temperature before taking a reading to avoid inaccuracies caused by temperature gradients.
Step 3
Explain, in terms of particle behaviour, why the resistance of the nichrome wire changes as temperature increases.
Answer
As the temperature of the nichrome wire increases, the kinetic energy of the lattice ions also increases. This causes the ions to vibrate more vigorously, leading to a higher frequency of collisions between the moving electrons and the lattice ions. The increased collisions result in a higher resistance due to the increased difficulty for electrons to flow through the wire. Additionally, as the temperature rises, the average velocity of the electrons increases, which also contributes to the changes in resistance. Thus, the overall effect is that the resistance of the nichrome wire increases with temperature.