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Questions on the Photoelectric Effect

Q10. Sodium metal has a work function of 2.28 eV. An atom of sodium has an ionisation energy of 5.15 eV.

(a)

(i) State what is meant by work function.

[2 marks]

(ii) State what is meant by ionisation energy.

[2 marks]

(b) Show that the minimum frequency of electromagnetic radiation needed for a photon to ionise an atom of sodium is about 1.2 × 1015 Hz.

[2 marks]

(c) Electromagnetic radiation with the frequency calculated in part (b) is incident on the surface of a piece of sodium.

Calculate the maximum possible kinetic energy (in joules) of an electron that is emitted when a photon of this radiation is incident on the surface.

Give your answer to an appropriate number of significant figures.

[3 marks]

(d) Calculate the speed of an electron that has the same de Broglie wavelength as the electromagnetic radiation in part (b).

[3 marks]

(Total 12 marks)