AQA A-Level Physics Paper 1, June 2023: Question 21
1 mark · Easy difficulty · Multiple Choice
Identify the correct statement about a superconducting metal from a multiple-choice list.
Practise this questionQuestion
Question text
21 Which statement about a superconducting metal is correct?
[1 mark]
A Its resistivity is small but not zero.
B A current in it causes no heating effect.
C Its critical temperature is independent of the metal it is made from.
D Keeping it cold makes it too expensive to use.
Mark scheme
Show the mark scheme
21 B A current in it causes no heating effect.
How to answer it
Properties of Superconducting Metals
What this question tests
This question assesses your understanding of superconductivity, including the defining characteristic of zero electrical resistivity, the resultant absence of thermal energy dissipation (heating effect) when carrying a current, and the material-dependent nature of critical temperatures.
Exam Question Analysis
✅ Correct Answer: B
A current in it causes no heating effect.
Because a superconductor has zero electrical resistance (and zero resistivity) when cooled below its critical temperature, power dissipation (P = I²R) is zero. Therefore, no thermal energy is generated when a current passes through it.
💡 Key Knowledge
- Resistivity: A superconductor has zero resistivity, not just a small one.
- Critical Temperature (Tc): Each superconducting material has a specific, characteristic critical temperature below which it transitions into a superconductor.
- Applications: While cooling systems can be expensive, superconductivity is used precisely because eliminating resistance prevents energy losses in high-current applications like MRI scanners and particle accelerators.
🧠 Exam Technique
For multiple-choice definitions, evaluate each option systematically against fundamental physical laws. Rule out incorrect absolute statements (e.g., resistivity being "small but not zero") using your core definitions.
❌ Common Errors
- Confusing superconductors with very good normal conductors (like cold copper), which still have a small, non-zero resistance.
- Assuming critical temperature is a universal constant rather than depending entirely on the specific material used.
Topics
Physics · 3.5 Electricity
Question and mark scheme from the AQA A-Level Physics examination, Paper 1, June 2023. QuestionVault is an independent revision resource; questions remain the copyright of the awarding body.