Describe the process of nuclear fusion and explain why it requires extremely high temperatures to occur.
Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).
Model answer (4 marks)
Nuclear fusion is the joining of two light nuclei to form a heavier nucleus, releasing energy.
High temperatures are required because the positively charged nuclei repel each other.
The thermal energy at high temperatures gives the nuclei enough kinetic energy to overcome this electrostatic repulsion and approach closely enough to fuse.
High temperatures are required because the positively charged nuclei repel each other.
The thermal energy at high temperatures gives the nuclei enough kinetic energy to overcome this electrostatic repulsion and approach closely enough to fuse.
Examiner tips
- Use the exact phrase "joining of two light nuclei" and "releasing energy" to hit the key points. Show the cause–effect link: high temperature → kinetic energy → overcomes repulsion. Keep the answer short and to the point – 4 marks can be earned with two short sentences.
- common_mistakes
- :
- Using vague terms like "big nuclei" instead of "light nuclei". Forgetting to mention that energy is released. Not explaining that the repulsion is electrostatic or that temperature provides kinetic energy.
Mark scheme (4 marks)
- Nuclear fusion is the joining/combining of two light nuclei to form a larger/heavier nucleus
- Energy is released during nuclear fusion
- High temperatures are needed because nuclei are positively charged and repel each other
- High temperatures give the nuclei enough kinetic energy to overcome this repulsion and get close enough to fuse
Key terms in this question
Related
- All Eduqas GCSE Physics revision notes →
- How to answer a "Describe" question →
- Decode the mark scheme abbreviations →
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