Particles and Radiation

AQA AS-level PhysicsTopic 2 of 1422 lessons

Revision notes for Particles and Radiation in AQA Physics (7407). Every lesson in BrainCake comes with R.E.C.I.P.E. recall steps, a quick check and spaced reviews.

1. Structure of the AtomThe atom is made of a positively charged nucleus made of protons and neutrons.
2. IsotopesIsotopes are atoms of the same element with the same number of protons but a different number of neutrons.
3. Specific ChargeThe specific charge of a particle is its charge per unit mass.
4. The Strong Nuclear ForceThe strong nuclear force overcomes the electrostatic force of repulsion between protons in the nucleus and holds neutrons and protons together.
5. Forces in the NucleusStable nuclei do not disintegrate.
6. Radioactive DecaySome naturally occurring isotopes are unstable and spontaneously emit alpha or beta radiation in order to gain stability.
7. Alpha RadiationAn alpha particle is a helium nucleus, made of 2 protons and 2 neutrons.
8. Beta RadiationBeta particles are fast-moving electrons or positrons from the nucleus.
9. Gamma Radiation and Electromagnetic WavesElectromagnetic radiation emitted by an unstable nucleus when the nucleus has too much energy following α or β emission.
10. The Electron VoltThe energy of small particles is often expressed in millions of electron volts.
11. PhotonsElectromagnetic waves are emitted when charged particles lose energy e.g. when fast moving electrons are stopped by collision in an X-ray tube, slow…
12. Anti-matterFor every type of particle there is a corresponding anti-particle which has exactly the same rest mass as the particle but opposite charge.
13. AnnihilationAnnihilation occurs when a particle and its corresponding antiparticle meet.
14. Pair ProductionIf a photon with sufficient energy passes near a nucleus or an electron, it can suddenly change into a particle-antiparticle pair which would then…
15. The Discovery of the PositronAmerican physicist Carl Anderson was using a cloud chamber to examine trails left by cosmic rays.
16. The Electromagnetic ForceTwo charged particles with the same charge such as protons repel each other and move away from each other.
17. Feynman DiagramsFeynman Diagrams are graphical representations of the interactions of elementary particles.
18. The Weak Nuclear ForceThe weak nuclear force causes neutrons to change into protons in β-minus decay and causes protons to change into neutrons in β-plus decay.
19. The W BosonW bosons are the exchange particles for the weak interaction.
20. Beta DecayIn beta-minus decay, a neutron changes into a proton, β-minus particle(electron) and an antineutrino.
21. Electron CaptureIn electron capture, a proton in a proton-rich nucleus interacts through the weak interaction with an inner shell electron from outside the nucleus…
22. Force CarriersThe photon and W bosons are force carriers because they are exchanged when the electromagnetic and weak nuclear force act.

On the specification

• 3.2.1.1 Constituents of the atom
• 3.2.1.2 Stable and unstable nuclei
• 3.2.1.3 Particles, antiparticles and photons
• 3.2.1.4 Particle interactions
• 3.2.1.5 Classification of particles

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