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A photocell cathode is made of a metal with a work function of 2.8 eV. Light of wavelength 430 nm shines on the cathode. (a) (b) (c) State and explain, using appropriate calculations, whether the electrons will be emitted from the cathode or not. An electron is accelerated between two plates with a potential difference of 4 kV. Determine the de Broglie wavelength of the electron. The diagram below shows some of the energy levels of the mercury atom. 0 lonisation level -1.6 -3.7 Energy / ev -5.5 -10.4 i. Calculate the ionisation energy, in J, for an electron in the -10.4 eV level. ii. An electron has been excited to the -3.7 eV level. Copy the diagram and show all the possible ways it can return to the - 10.4 eV level. iii. Which change in energy levels will give rise to a yellowish line (λ = 600 nm) in the mercury spectrum?