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Nuclear Fission and Nuclear Fusion: Source of Energy — Syllabus

ICSE · Class 12 · Physics

What Nuclear Fission and Nuclear Fusion: Source of Energy covers in ICSE Class 12 Physics: 4 topics, for the 2026-27 session.

69 questions36 flashcards9 formulas & key relations5 concepts

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A step-by-step diagram illustrating the process of nuclear fission, specifically a chain reaction initiated by a neutron striking a Uranium-235 nucleus, leading to the release of energy and more neutr
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4 Topics · ICSE Class 12 Physics · 2026-27

Topics in Nuclear Fission and Nuclear Fusion: Source of Energy

1

1. Nuclear Fission

  • In 1939, Hahn and Strassmann observed that when uranium nucleus with atomic number 92 was bombarded with neutrons, it split into isotopes of barium and krypton.
  • Meitner and Frisch named this phenomenon nuclear fission.
  • Nuclear fission is a process in which a heavy nucleus, after capturing a thermal neutron of energy 0.027 eV, splits up into two lighter nuclei of comparable masses.
2

2. Chain Reaction, Critical Size, and Multiplication Factor

  • A chain reaction starts when neutrons produced in one fission cause further fissions.
  • If more than one emitted neutron causes further fission, the reaction grows rapidly and becomes uncontrolled.
  • If the reaction is controlled so that, on average, only one neutron continues the chain, the reaction remains steady.
3

3. Nuclear Reactor and Its Parts

  • A nuclear reactor is a device in which a self-sustaining controlled chain reaction is produced in a fissionable material.
  • The main fuel used is uranium enriched with U-235 or Pu-239.
  • A moderator slows fast neutrons to thermal energies by elastic collisions.
4

4. Production of Plutonium-239 and Reactor Types

  • In a reactor, neutrons not used in the fission chain reaction can be absorbed by U-238 to form U-239.
  • U-239 is unstable and beta decays into Np-239.
  • Np-239 also beta decays into Pu-239.

Key Concepts

Central concept: Nuclear energy from fission, fusion, and controlled chain reactions

Nuclear fissionFission of U-235Fission of U-238Chain reactionMultiplication or reproduction factor KCritical size and critical massModeratorsControl rods

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Frequently Asked Questions

What are the important topics in Nuclear Fission and Nuclear Fusion: Source of Energy for ICSE Class 12 Physics?
Key topics in Nuclear Fission and Nuclear Fusion: Source of Energy include Nuclear Fission, Chain Reaction, Critical Size, and Multiplication Factor, Nuclear Reactor and Its Parts, Production of Plutonium-239 and Reactor Types. Study these first, then practise questions on each for the ICSE Class 12 board exam.
How should I revise Nuclear Fission and Nuclear Fusion: Source of Energy for the ICSE Class 12 board exam?
Learn the core ideas first, then work through the 69 practice questions on Nuclear Fission and Nuclear Fusion: Source of Energy. Revise definitions regularly and use flashcards for quick recall before the exam.

Sources & Official References

Content is aligned to the official syllabus. Refer to the board website for the latest curriculum.

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