A-LevelPhysicsQuantum physics9702/42 · Feb/Mar 2020 · Q107 Marks

10 (a) By reference to the photoelectric effect, explain what is meant by work function energy. (b) In an experiment, electromagnetic radiation of frequency f is incident on a metal surface. The results in Fig. 10.1 show the variation with frequency f of the maximum kinetic energy E_MAX of electrons emitted from the surface. [Figure 10.1]

(a)By reference to the photoelectric effect, explain what is meant by work function energy. [2][2]
(b)(i)Determine the work function energy in J of the metal used in the experiment. work function energy = ................................................................ J [2][2]
(b)(ii)The work function energy in eV for some metals is given in Table 10.1. [Table 10.1] Determine the metal used in the experiment. Show your working. [1][1]
(c)(i)the maximum kinetic energy of the emitted electrons [1][1]
(c)(ii)the rate of emission of photoelectrons. [1][1]

This question uses a diagram from the original paper, which isn't shown here. Open the full paper from the past papers archive to see it.

Mark scheme

Marking points from the official mark scheme (Feb/Mar 2020). The mark or mark type is shown in brackets.

[1] energy of a photon required to remove an electron
[1] energy to remove electron from a surface / minimum energy to remove electron / energy to remove electron with zero kinetic energy
[1] Correct read off from graph of f as 5.45 × 10¹⁴ Hz when E_MAX = 0
[1] 5.45 × 10¹⁴ × 6.63 × 10⁻³⁴ = 3.6 × 10⁻¹⁹ J
[1] 3.6 × 10⁻¹⁹ / 1.6 × 10⁻¹⁹ = 2.3 eV so potassium
[1] each photon has same energy so no change
[1] more photons (per unit time) so (rate of emission) increases

On Oracle Prep you can write or photograph your own answer and have it marked by AI against this mark scheme, with feedback on what you missed.