Excitation vs Ionisation: Electron Collisions with Atoms | A-Level Physics

Why can one incoming electron bounce away, excite an atom or ionise it? This AQA-first AS and A-level Physics lesson tracks the energy changes step by step. You will learn how to: • distinguish the incident free electron from an electron bound inside the atom • separate elastic scattering, excitation and ionisation • use threshold energy without assuming a collision outcome is guaranteed • define the electronvolt and convert between electronvolts and joules • explain how electron collisions in mercury vapour lead to visible light in a fluorescent tube The electronvolt and energy-level ideas are also useful across other A-level specifications, while the full fluorescent-tube collision chain is taught here as an AQA application. The notes for this video can be found at: https://inklearning.co.uk/physics/qua... Chapters 00:00 Three collision outcomes 00:12 The two different electrons 00:26 Elastic collisions 00:44 Excitation and energy transfer 01:23 Ionisation 01:34 Thresholds and possible outcomes 02:25 Electronvolts and joules 03:08 Inside a fluorescent tube 04:08 Recap and conservation of energy 04:43 Next: Energy Levels and Photon Emission Continue with InkPhysics: Energy Levels and Photon Emission. Subscribe for more visual A-level Physics explanations. #ALevelPhysics #AtomicPhysics #InkPhysics