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4 marksParticulate Nature of Electromagnetic Radiation

CAPE Physics Unit 2 · May/June 2023 · Paper 2 · Question 3(b)

Figure 7 shows apparatus for a photoelectricity experiment. S is a variable frequency UV light source, and the cathode is a polished metal surface. The potential difference between anode and cathode is measured by a voltmeter and can be varied. Photoelectric current is measured by a microammeter.

With reference to the apparatus in Figure 7, explain the meaning of the term 'stopping potential'.

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Other parts of this question

  1. 3(a)(i)Define EACH of the following terms. Work function[2 marks]
  2. 3(a)(ii)Threshold frequency[1 mark]
  3. 3(a)(iii)Cut-off wavelength[1 mark]
  4. 3(c)(i)Write the general form of the photoelectric equation and rearrange it to show the linear relationship between stopping potential, V_s, and frequency, f, as…[2 marks]
  5. 3(c)(ii)Determine the gradient of the line in Figure 8.[3 marks]
  6. 3(c)(iii)Determine the percentage difference between the experimental value of h/e obtained in (c) (ii) and the calculated theoretical value of h/e (using the standard…[3 marks]
  7. 3(c)(iv)Comment on the result obtained in (c) (iii).[2 marks]
  8. 3(c)(v)Extrapolate the line on the graph in Figure 8 on page 19, to find the intercept on the V_s axis and use this value to determine the work function of the…[5 marks]
  9. 3(d)(i)For EACH of the labelled regions on the graph in Figure 9, state what happens to the flow of the photocurrent and explain why this happens in EACH case.…[2 marks]
  10. 3(d)(ii)Region B[2 marks]
  11. 3(d)(iii)Region C[3 marks]

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