Available practice: 77 of 100 marks. Parts 1(b), 4(b)(i), 4(c), 6(a)(ii), 6(b)(ii), 7(a)(i), 7(a)(ii), 9(b)(i), 9(c), 10(b)(ii) await marking support. Scores cover available parts only.
(a)Describe two phenomena associated with the photoelectric effect that cannot be explained using a wave theory of light.
Answer guidance
Describe Say what happens, in order. Reasons are not required unless the question also asks why.
[2 marks]
The maximum energy E_max of electrons emitted from a metal surface when illuminated by light of wavelength λ is given by the expression E_max = hc(1/λ − 1/λ₀), where h is the Planck constant and c is the speed of light.
(b)(i)Identify the symbol λ₀.
Answer guidance
Identify Name it and, where the marks allow, say what led you there.
[1 mark]
The maximum energy E_max of electrons emitted from a metal surface illuminated by light of wavelength λ is E_max = hc(1/λ − 1/λ₀). The variation with 1/λ of E_max for the metal surface is shown in Fig. 8.1.
(b)(ii)Use Fig. 8.1 to determine the magnitude of λ₀.
Answer guidance
Using You must use the thing it names. An answer that reaches the right value another way may not score.
[1 mark]
The maximum energy E_max of electrons emitted from a metal surface illuminated by light of wavelength λ is E_max = hc(1/λ − 1/λ₀).
(b)(iii)Use the gradient of Fig. 8.1 to determine a value for the Planck constant h. Show your working.
Answer guidance
Show The result is given, so every step of the reasoning is what earns the marks.
[3 marks]
The metal surface becomes oxidised. Photoelectric emission is still observed but the work function energy is increased.
(c)On Fig. 8.1, draw a line to show the variation with 1/λ of E_max for the oxidised surface.
[2 marks]
9702/04/SP/22Cambridge International AS & A Level Physics 9702 · Specimen 2022 · Paper 4 · Question 8
