What is fusion?
- The joining of two small, light nuclei to form a larger nucleus
- Releases even MORE energy than fission (per kg of fuel)
- Powers the Sun and all stars
- Potential for clean energy on Earth — but extremely difficult to achieve
Fusion in the Sun (Hydrogen → Helium):
²H + ³H → ⁴He + neutron + ENERGY
● + ● → ⬤ + ○ + ⚡⚡⚡⚡
(deuterium + tritium → helium-4 + neutron + 17.6 MeV)
Why fusion is hard on Earth:
- Nuclei are positively charged — they repel each other
- Need extremely high temperature (100+ million °C) to overcome repulsion
- Need extremely high pressure to force nuclei close together
- The Sun has enormous gravity to provide pressure — we don't!
- Containing plasma at 100 million °C without it touching anything is very challenging
This key facts covers Nuclear Fusion — Key Details within Nuclear Fission & Fusion for GCSE Physics. Revise Nuclear Fission & Fusion in Atomic Structure for GCSE Physics with 13 exam-style questions and 25 flashcards. This topic appears less often, but it can still be a useful differentiator on mixed-topic papers. It is section 8 of 18 in this topic. Use this key facts to connect the idea to the wider topic before moving on to questions and flashcards.
Practice questions for Nuclear Fission & Fusion
What is nuclear fission?
Explain what is meant by a chain reaction in nuclear fission.