Physics A-Level
Pair annihilation
What Pair annihilation means in Physics A-Level, as defined for OCR.
Definition of Pair annihilation
Check what you remember
Read the wording for your board, then hide it and explain Pair annihilation in your own words. Rough notes are fine. This is a self-check, with no mark or grade.
Reference: OCR
A particle and its antiparticle combine and their mass is converted into photons, commonly two gamma-ray photons each of energy m₀c² emitted in opposite directions to conserve momentum.
Topics that use Pair annihilation
- Nuclear fission and fusion (OCR A-Level)
Related terms
- Alpha and beta decay
- Barium
- Binding energy
- Binding energy per nucleon against nucleon number curve
- Chain reactions
- Characteristic X-rays from shell transitions
- Compton effect
- Computer reconstruction of attenuation data
Using Pair annihilation in the exam
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