Fission And Fusion
Overview
The energy that powers nuclear reactors and the energy that keeps stars shining come from the same place: the nucleus. Splitting heavy nuclei apart (fission) and squeezing light nuclei together (fusion) both release enormous amounts of energy compared to any chemical reaction.
In this lesson you will learn how uranium-235 undergoes fission, how a chain reaction works, the roles of control rods, the moderator and shielding in a reactor, what nuclear fusion is, why it powers stars, and why achieving fusion on Earth is so difficult.
Objectives
- Know that nuclear reactions, including fission, fusion and radioactive decay, can be a source of energy
- Understand how a nucleus of U-235 can be split by collision with a neutron, and that this process releases energy
- Know that the fission of U-235 produces two radioactive daughter nuclei and a small number of neutrons
- Describe how a chain reaction can be set up if the neutrons produced by one fission strike other U-235 nuclei
- Describe the role played by the control rods and moderator in the fission process
- Understand the role of shielding around a nuclear reactor
- Explain the difference between nuclear fusion and nuclear fission
- Describe nuclear fusion as the creation of larger nuclei from smaller nuclei, accompanied by a release of energy
- Know that fusion is the energy source for stars
- Explain why nuclear fusion does not happen at low temperatures and pressures
Mind map
This topic is mapped out so you can see how the ideas connect.
Open the mind map in the app
Flashcards
Quick recall practice on the facts this topic is tested on.
Practise these cards in the app
Lesson Note
Complete Note Available on the Green Bridge App
Get the Green Bridge CBT app on your phone or computer for the complete IGCSE library: past papers, mark schemes, mind maps, flashcards and audio lessons.
Lesson Evaluation
Congratulations on completing the lesson on Fission And Fusion. Now that youve explored the key concepts and ideas, its time to put your knowledge to the test. This section offers a variety of practice questions designed to reinforce your understanding and help you gauge your grasp of the material.
You will encounter a mix of question types, including multiple-choice questions, short answer questions, and essay questions. Each question is thoughtfully crafted to assess different aspects of your knowledge and critical thinking skills.
Use this evaluation section as an opportunity to reinforce your understanding of the topic and to identify any areas where you may need additional study. Don't be discouraged by any challenges you encounter; instead, view them as opportunities for growth and improvement.
- In nuclear fission, a heavy nucleus: A) Absorbs light B) Splits into two smaller nuclei C) Fuses with another nucleus D) Emits only gamma rays Answer: B
- The role of control rods in a reactor is to: A) Speed up neutrons B) Absorb neutrons C) Produce neutrons D) Shield workers Answer: B
- Nuclear fusion is the energy source of: A) Nuclear power stations B) Coal-fired stations C) Stars D) Batteries Answer: C
- Fusion requires very high temperatures because: A) Nuclei are negatively charged B) Nuclei are neutral C) Positive nuclei repel each other D) Neutrons need to be fast Answer: C
- The moderator in a reactor: A) Absorbs neutrons completely B) Speeds up neutrons C) Slows down neutrons D) Generates neutrons Answer: C
Work through these questions in the app
Work through these questions in the app
Practice Mock Questions
Want to practice mock questions on Fission And Fusion? Download the Green Bridge CBT app to access mock questions and full practice assessments for this topic.
Download The App On Google Playstore
Everything you need to excel in your exams
