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Module 4: Electrons, waves and photons

4.5 Quantum physics

4.5.1 Photons	(a) the particulate nature (photon model) of electromagnetic radiation	Structured Questions Multiple choice
	(b) photon as a quantum of energy of electromagnetic radiation
	(c) energy of a photon; E = hf and E = hc/λ
	(d) the electronvolt (eV) as a unit of energy
	(e) (i) using LEDs and the equation eV = hc/λ to estimate the value of Planck constant h		No knowledge of semiconductor theory is required.
	(e) (ii) Determine the Planck constant using different coloured LEDs.
4.5.2 The photoelectric effect	(a) (i) photoelectric effect, including a simple experiment to demonstrate this effect	Multiple choice Structured Questions	You should understand that this provides evidence for particulate nature of electromagnetic radiation.
	(a) (ii) demonstration of the photoelectric effect using, e.g. gold-leaf electroscope and zinc plate
	(b) a one-to-one interaction between a photon and a surface electron		You should do internet research on the development of quantum physics.
	(c) Einstein's photoelectric equation hf = φ + KE_max
	(d) work function φ; threshold frequency
	(e) the idea that the maximum kinetic energy of the photoelectrons is independent of the intensity of the incident radiation
	(f) the idea that rate of emission of photoelectrons above the threshold frequency is directly proportional to the intensity of the incident radiation.
4.5.3 Wave–particle duality	(a) electron diffraction, including experimental evidence of this effect		You should understand that electron diffraction provides evidence for wave-like behaviour of particles.
	(b) diffraction of electrons travelling through a thin slice of polycrystalline graphite by the atoms of graphite and the spacing between the atoms
	(c) the de Broglie equation λ_dB = h/p	Multiple choice	Structured Questions