This key facts covers Chain Reactions 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 6 of 18 in this topic. Use this key facts to connect the idea to the wider topic before moving on to questions and flashcards.
⛓️ Chain Reactions
What is a chain reaction?
- Each fission releases 2-3 neutrons
- These neutrons can cause more fissions
- Each of those releases more neutrons → more fissions → exponential growth!
Chain Reaction:
1 fission → 3 neutrons → 3 fissions → 9 neutrons → 9 fissions...
⬤ → ●●● → ⬤⬤⬤ → ●●●●●●●●● → ⬤⬤⬤⬤⬤⬤⬤⬤⬤ → 💥
Numbers: 1 → 3 → 9 → 27 → 81 → 243... (exponential growth!)
Types of chain reaction:
- Controlled: Nuclear power station — chain reaction maintained at steady rate
- Uncontrolled: Nuclear bomb — chain reaction grows exponentially → explosion
Practice questions for Nuclear Fission & Fusion
What is nuclear fission?
Explain what is meant by a chain reaction in nuclear fission.