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2 marksParticulate Nature of Electromagnetic Radiation

CAPE Physics Unit 2 · 2008 (Rest of Region) · Paper 2 · Question 3(a)(iii)

A photocell circuit and its current-voltage characteristic are shown in Figure 3a and Figure 3b.

Explain why the current stays constant between X and Y on the graph.

This question uses a figure or table from the paper — you'll see it when you practise.

The mark scheme is shown once you've answered.

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Other parts of this question

  1. 3(a)(i)Add a curve to Figure 3a showing the effect of increasing the light intensity, and label it A.[1 mark]
  2. 3(a)(ii)Add another curve to Figure 3a labelled B showing the expected result if radiation with shorter wavelength is used.[1 mark]
  3. 3(a)(iv)Explain why the current decreases when the voltage across the tube is reversed (region XZ).[1 mark]
  4. 3(a)(v)State how the stopping potential can be used to calculate the maximum kinetic energy of the photoelectrons.[1 mark]
  5. 3(b)(i)Plot a suitable graph on the grid provided using the given data of E_{\max} and frequency f, and determine the value of Planck's constant h.[7 marks]
  6. 3(b)(ii)Calculate the value of the work function for this photocathode.[2 marks]

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