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Date May 2021 Marks available 2 Reference code 21M.2.HL.TZ2.9
Level Higher level Paper Paper 2 Time zone 2
Command term Calculate Question number 9 Adapted from N/A

Question

In an experiment to demonstrate the photoelectric effect, monochromatic electromagnetic radiation from source A is incident on the surfaces of metal P and metal Q. Observations of the emission of electrons from P and Q are made.

The experiment is then repeated with two other sources of electromagnetic radiation: B and C. The table gives the results for the experiment and the wavelengths of the radiation sources.

Outline the cause of the electron emission for radiation A.

[1]
a.i.

Outline why electrons are never emitted for radiation C.

[1]
a.ii.

Outline why radiation B gives different results.

[1]
a.iii.

Explain why there is no effect on the table of results when the intensity of source B is doubled.

[1]
b.

Photons with energy 1.1 × 10−18 J are incident on a third metal surface. The maximum energy of electrons emitted from the surface of the metal is 5.1 × 10−19 J.

Calculate, in eV, the work function of the metal.

[2]
c.

Markscheme

photon transfers «all» energy to electron 

a.i.

photon energy is less than both work functions
OR
photon energy is insufficient «to remove an electron»


Answer must be in terms of photon energy.

a.ii.

Identifies P work function lower than Q work function

a.iii.

changing/doubling intensity «changes/doubles number of photons arriving but» does not change energy of photon

b.

5.1×10-19=1.1×10-18-ϕ ✓

work function = «(11.0-5.1)×10-191.6×10-19= » 3.7 «eV»  ✓


Award [2] marks for a bald correct answer.

c.

Examiners report

[N/A]
a.i.
[N/A]
a.ii.
[N/A]
a.iii.
[N/A]
b.
[N/A]
c.

Syllabus sections

Additional higher level (AHL) » Topic 12: Quantum and nuclear physics » 12.1 – The interaction of matter with radiation
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Additional higher level (AHL) » Topic 12: Quantum and nuclear physics
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