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Useful background |
You should be able to: |
The photoelectric effect
Work function  , photoelectric equation hf = + Ek; (the stopping potential experiment is not required) |
(QUESTIONS: L&R Ex 137 Q1, Q2, Q4, Q5) |
- Explain the underlying principles behind the photoelectric effect, including a derivation of Einstein’s equation in terms of energy conservation
- Understand the term photon and calculate the number of photons in a light beam
- Derive the equation: hf = + Ek
- Explain that the work function is the energy with which each electron is bound to the surface of the metal (and therefore the energy that is required to release it from the metal)
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Collisions of electrons with atoms: Ionisation, excitation
The electronvolt
Understanding of the role of ionisation and excitation in the fluorescent tube;
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- Recall the structure of the atom to include the energy level model for electrons
- Recall the definition of the electronvolt |
| Energy levels and photon emission line spectra - absorption and emission (e.g. of atomic hydrogen) as evidence of transitions between discrete energy levels
Energy levels, photon emission : hf = E1 - E2 |
Ciccotti and Kelly pp 72-79
L&R Ex136 Q1, 2, 5, 7
L & R Ex 137 Q8
Muncaster G19-G21 |
- Explain the difference between ionisation and excitation and apply this to the operation of a fluorescent tube
- Explain the origin of line spectra and use this as evidence to support the model of discrete energy levels
- Recall the equation hf = E1 - E2
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Wave-particle duality
Candidates should know that electron diffraction suggests the wave nature of particles and the photoelectric effect suggests the particle nature of electromagnetic waves; (details of particular methods of showing particle diffraction are not expected)
de Broglie wavelength
where mv is the momentum p
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Ciccotti and Kelly pp 83
L&R Ex136 Qn6
L&R Ex137 Q6 and 7 |
- Recall the evidence for wave and particle behaviour in light and matter and indicate practical methods that can be used to demonstrate these properties
- Recall the equation for the de Broglie wavelength
- Recognise the effect of particle speed on wavelength and the potential diffraction effect that could be obtained
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