Wave-Particle Duality

What Wave-Particle Duality covers

Wave-Particle Duality is examined in Unit AS 2, Waves, Photons and Astronomy, and drawn on again in Unit AS 3, Practical Techniques and Data Analysis. It covers wave model, photon model and both, electron diffraction, the de Broglie wavelength and calculations with the de Broglie equation.

The 4 subtopics

Each one has its own page. CCEA AS Physics students sit this topic in the first year.

• Wave model, photon model and bothRecall questions on what wave-particle duality means, which properties of light the wave model explains, which effects need the photon model, which are explained by either, and the case-by-case classification of diffraction, the photoelectric effect, Young's fringes, line spectra, polarisation and reflection.Open →
• Electron diffractionRecall questions on the electron diffraction tube and what is seen on its screen, why a ring pattern rather than spots appears, why a crystal is used rather than a slit, how the ring size changes with the accelerating voltage and how that supports de Broglie, why a cricket ball cannot be diffracted, and why the tube must be evacuated.Open →
• The de Broglie wavelengthDe Broglie equation, defining every symbol with its unit and de Broglie's hypothesis.Open →
• Calculations with the de Broglie equationRecall questions applying λ = h/mv to an electron, a proton, a neutron, a cricket ball and a walking person, working back from a wavelength to a speed or a momentum, the derivation of λ = h/√(2meV) for an accelerated electron, and why about 100 V is a suitable accelerating voltage for a demonstration.Open →

What you need to know

Answer each one before you reveal it.

Take Wave-Particle Duality further

The same content, four other ways.

Questions from this topic

Each one with the model answer underneath.

1. 1

   What is meant by wave-particle duality?

   Model answer

   Wave-particle duality is the idea that electromagnetic radiation and matter each show wave behaviour in some experiments and particle behaviour in others, and that a complete description needs both models.

2. 2

   Name three properties of light that are explained by the wave model.

   Model answer

   Diffraction, interference and polarisation are all explained by the wave model and cannot be explained by treating light as a stream of particles.

3. 3

   Name two effects that require the photon model rather than the wave model.

   Model answer

   The photoelectric effect and the production of line spectra both require the photon model, because each depends on radiation delivering its energy in discrete amounts.

4. 4

   Name two behaviours of light that can be explained by either model.

   Model answer

   Reflection at a plane surface and refraction at a boundary can both be described successfully by the wave model or by the photon model.

5. 5

   Is the formation of a diffraction grating pattern explained by the wave model, the photon model or both?

   Model answer

   By the wave model, because the sharp beams arise from the superposition of waves from many slits arriving in phase.

6. 6

   Is the photoelectric effect explained by the wave model, the photon model or both?

   Model answer

   By the photon model only, because the threshold frequency and the instant emission cannot be reconciled with energy arriving as a continuous wave.

What is inside Levo

Six ways to work the same material.

Wave-Particle Duality revision questions

Is Wave-Particle Duality examined at AS in CCEA Physics?

Yes. It sits in Unit AS 2, which you take in the first year, so it is on the AS paper as well as counting towards the full A level.

What does Wave-Particle Duality cover in CCEA AS-Level Physics?

4 subtopics: wave model, photon model and both, electron diffraction, the de broglie wavelength and calculations with the de broglie equation. Each one has its own page with questions and model answers.

How is Wave-Particle Duality organised?

By the CCEA 1210 specification, subtopic by subtopic, so it matches the order you are taught it in.