Nuclear Fusion (OCR A Level Physics): Revision Note

Exam code: H556

Katie M

Author

Katie M

Last updated

Nuclear Fusion

  • Fusion is defined as:

    Small nuclides combine together to make larger nuclei, releasing energy

  • Low mass nuclei (such as hydrogen and helium) can undergo fusion and release energy

The fusion of deuterium and tritium to form helium with the release of energy

  • For two nuclei to fuse, both nuclei must have high kinetic energy

    • This is because the protons inside the nuclei are positively charged, which means that they repel one another

  • It takes a great deal of energy to overcome the electrostatic force, so this is why it can only be achieved in an extremely high-energy environment, such as a star’s core

  • When two protons fuse, the element deuterium is produced

  • In the centre of stars, the deuterium combines with a tritium  nucleus to form a helium nucleus, plus the release of energy, which provides fuel for the star to continue burning

Examiner Tips and Tricks

In the fusion process, the mass of the new heavier nucleus is less than the mass of the constituent parts of the nuclei fused together, as some mass is converted into energy. 

Not all of this energy is used as binding energy for the new larger nucleus, so energy will be released from this reaction. The binding energy per nucleon afterwards is higher than at the start. 

For teachers

Ready to test your students on this topic?

  • Create exam-aligned tests in minutes
  • Differentiate easily with tiered difficulty
  • Trusted for all assessment types
Explore Test Builder
Test Builder in a diagram showing questions being picked from different difficulties and topics, and being downloaded as a shareable format.
Katie M

Author: Katie M

Expertise: Physics Content Creator

Katie has always been passionate about the sciences, and completed a degree in Astrophysics at Sheffield University. She decided that she wanted to inspire other young people, so moved to Bristol to complete a PGCE in Secondary Science. She particularly loves creating fun and absorbing materials to help students achieve their exam potential.