(HL) Quantum physics

Learning objectives

(HL) Describe the photoelectric effect, and explain why a threshold frequency, the immediate emission of electrons and the independence of maximum kinetic energy from intensity cannot be accounted for by a wave model of light

(HL) Apply Einstein's photoelectric equation Emax = hf − Φ, relate the maximum kinetic energy to the stopping voltage through Emax = eVs, and determine the Planck constant and the work function from a graph of stopping voltage against frequency

(HL) Describe the Compton scattering of an X-ray photon by a free electron, and calculate the shift in wavelength from Δλ = (h/mec)(1 − cosθ)

(HL) Apply the de Broglie relation λ = h/p to matter waves, and explain how the diffraction of electrons by a thin crystal provides experimental evidence for the wave nature of particles

(HL) Describe quantum tunnelling as the passage of a particle through a potential barrier it has too little energy to surmount classically, and explain qualitatively how the transmission probability depends on the mass of the particle, the width of the barrier and the energy difference

(HL) Explain the wave–particle duality of photons and of electrons, and select the model appropriate to a given experimental observation