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The discovery of the electron: AQA A‑Level Physics questions

Every AQA A-Level Physics exam question on 3.12.1 The discovery of the electron, 2016–2025, with its mark scheme and examiner’s report.

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2,714 questions

  1. Q01.1

    June 2025 · Paper 3 Turning points

    3 marks3.12.1 The discovery of the electron
    The whole paper ↗
    June 2025 Paper 3 Turning points, question 01.1: A modern version of Thomson’s apparatus uses thermionic emission in the production of the electron beam. Suggest how the electron beam is produced in this moder

  2. Q01.2

    June 2025 · Paper 3 Turning points

    2 marks3.12.1 The discovery of the electron
    The whole paper ↗
    June 2025 Paper 3 Turning points, question 01.2: A uniform magnetic field of flux density 0.640 mT is now applied between the plates. This returns the electron beam to its undeflected position. Show that the h

  3. Q01.3

    June 2025 · Paper 3 Turning points

    1 mark3.12.1 The discovery of the electron
    The whole paper ↗
    June 2025 Paper 3 Turning points, question 01.3: Show that the vertical component of the velocity of the electrons at T is approximately 1.1 × 107 m s−1. [1 mark]

  4. Q01.4

    June 2025 · Paper 3 Turning points

    2 marks3.12.1 The discovery of the electron
    The whole paper ↗
    June 2025 Paper 3 Turning points, question 01.4: Show that the vertical acceleration of the electrons between the plates is approximately 2.5 × 1015 m s−2. [2 marks]

  5. Q01.5

    June 2025 · Paper 3 Turning points

    3 marks3.12.1 The discovery of the electron
    The whole paper ↗
    June 2025 Paper 3 Turning points, question 01.5: Determine a value for the specific charge of the electron. [3 marks] specific charge = C kg−1

  6. Q01.6

    June 2025 · Paper 3 Turning points

    2 marks3.12.1 The discovery of the electron
    The whole paper ↗
    June 2025 Paper 3 Turning points, question 01.6: Explain the significance of the result of Thomson’s determination. [2 marks]

  7. Q01.7

    June 2025 · Paper 3 Turning points

    3 marks3.12.1 The discovery of the electron
    The whole paper ↗
    June 2025 Paper 3 Turning points, question 01.7: Some students are given a version of the apparatus to repeat Thomson’s experiment. Figure 3 shows a section of the measuring scale on the fluorescent screen and

  8. Q01.1

    June 2024 · Paper 3 Turning points

    2 marks3.12.1 The discovery of the electron
    The whole paper ↗
    June 2024 Paper 3 Turning points, question 01.1: Figure 1 shows apparatus used in an experiment to measure the specific charge of the electron. Figure 1 Electrons are accelerated by the potential difference VA

  9. Q01.2

    June 2024 · Paper 3 Turning points

    4 marks3.12.1 The discovery of the electron
    The whole paper ↗
    June 2024 Paper 3 Turning points, question 01.2: Determine, using the following data, a value for the specific charge of the electron. B = 1.59 mT VP = 1.51 kV d = 5.0 cm VA = 1.00 kV [4 marks] specific charge

  10. Q02.1

    June 2024 · Paper 3 Turning points

    6 marks3.12.1 The discovery of the electron
    The whole paper ↗
    June 2024 Paper 3 Turning points, question 02.1: Figure 2 shows a cross-sectional view of the arrangement that Millikan used to determine the charge on the electron. Figure 2 Millikan’s initial step was to det

  11. Q02.2

    June 2024 · Paper 3 Turning points

    3 marks3.12.1 The discovery of the electron
    The whole paper ↗
    June 2024 Paper 3 Turning points, question 02.2: On one occasion, the radius of a droplet was determined to be 1.20 × 10−6 m. When the droplet was stationary, the voltmeter reading was 467 V. Show that the cha

  12. Q02.3

    June 2024 · Paper 3 Turning points

    3 marks3.12.1 The discovery of the electron
    The whole paper ↗
    June 2024 Paper 3 Turning points, question 02.3: Table 1 shows the percentage uncertainty in each quantity. Table 1 Quantity Percentage uncertainty radius of oil droplet 4% density of oil 1% gravitational fiel

  13. Q01.1

    June 2023 · Paper 3 Turning points

    1 mark3.12.1 The discovery of the electron
    The whole paper ↗
    June 2023 Paper 3 Turning points, question 01.1: Explain how the electrons that form the beam are emitted. [1 mark]

  14. Q01.2

    June 2023 · Paper 3 Turning points

    1 mark3.12.1 The discovery of the electron
    The whole paper ↗
    June 2023 Paper 3 Turning points, question 01.2: Show that the maximum speed of the electrons in the beam is about 1.3 × 107 m s−1. [1 mark]

  15. Q01.4

    June 2023 · Paper 3 Turning points

    6 marks3.12.1 The discovery of the electron
    The whole paper ↗
    June 2023 Paper 3 Turning points, question 01.4: In 1897, J J Thomson determined a value for the specific charge of an unknown particle. The unknown particle is now known to be the electron. Describe one metho

  16. Q02.1

    June 2023 · Paper 3 Turning points

    3 marks3.12.1 The discovery of the electron
    The whole paper ↗
    June 2023 Paper 3 Turning points, question 02.1: Calculate the viscosity of the air between the plates. [3 marks] viscosity = N s m−2

  17. Q02.2

    June 2023 · Paper 3 Turning points

    3 marks3.12.1 The discovery of the electron
    The whole paper ↗
    June 2023 Paper 3 Turning points, question 02.2: During the experiment, an electric field is produced between the plates and is adjusted until the oil drop is stationary. The electric field strength is 18.8 kV

  18. Q02.1

    June 2022 · Paper 3 Turning points

    1 mark3.12.1 The discovery of the electron
    The whole paper ↗
    June 2022 Paper 3 Turning points, question 02.1: State and explain the sign of the charge on the oil droplet. [1 mark] The variable voltage supply is set to zero volts. The oil drop falls. The constant speed v

  19. Q02.2

    June 2022 · Paper 3 Turning points

    3 marks3.12.1 The discovery of the electron
    The whole paper ↗
    June 2022 Paper 3 Turning points, question 02.2: Show that the mass m of the oil droplet is about 8 × 10−16 kg. [3 marks]

  20. Q02.3

    June 2022 · Paper 3 Turning points

    2 marks3.12.1 The discovery of the electron
    The whole paper ↗
    June 2022 Paper 3 Turning points, question 02.3: The variable voltage supply is adjusted so that the oil droplet rises at a constant speed v2. The potential difference (pd) across the plates is V and the dista
All 38 questions on The discovery of the electron, as a list
  1. June 2025, Paper 3 Turning points, Q01.1 (3 marks): A modern version of Thomson’s apparatus uses thermionic emission in the production of the electron beam. Suggest how the electron beam is produced in this moder
  2. June 2025, Paper 3 Turning points, Q01.2 (2 marks): A uniform magnetic field of flux density 0.640 mT is now applied between the plates. This returns the electron beam to its undeflected position. Show that the h
  3. June 2025, Paper 3 Turning points, Q01.3 (1 mark): Show that the vertical component of the velocity of the electrons at T is approximately 1.1 × 107 m s−1. [1 mark]
  4. June 2025, Paper 3 Turning points, Q01.4 (2 marks): Show that the vertical acceleration of the electrons between the plates is approximately 2.5 × 1015 m s−2. [2 marks]
  5. June 2025, Paper 3 Turning points, Q01.5 (3 marks): Determine a value for the specific charge of the electron. [3 marks] specific charge = C kg−1
  6. June 2025, Paper 3 Turning points, Q01.6 (2 marks): Explain the significance of the result of Thomson’s determination. [2 marks]
  7. June 2025, Paper 3 Turning points, Q01.7 (3 marks): Some students are given a version of the apparatus to repeat Thomson’s experiment. Figure 3 shows a section of the measuring scale on the fluorescent screen and
  8. June 2024, Paper 3 Turning points, Q01.1 (2 marks): Figure 1 shows apparatus used in an experiment to measure the specific charge of the electron. Figure 1 Electrons are accelerated by the potential difference VA
  9. June 2024, Paper 3 Turning points, Q01.2 (4 marks): Determine, using the following data, a value for the specific charge of the electron. B = 1.59 mT VP = 1.51 kV d = 5.0 cm VA = 1.00 kV [4 marks] specific charge
  10. June 2024, Paper 3 Turning points, Q02.1 (6 marks): Figure 2 shows a cross-sectional view of the arrangement that Millikan used to determine the charge on the electron. Figure 2 Millikan’s initial step was to det
  11. June 2024, Paper 3 Turning points, Q02.2 (3 marks): On one occasion, the radius of a droplet was determined to be 1.20 × 10−6 m. When the droplet was stationary, the voltmeter reading was 467 V. Show that the cha
  12. June 2024, Paper 3 Turning points, Q02.3 (3 marks): Table 1 shows the percentage uncertainty in each quantity. Table 1 Quantity Percentage uncertainty radius of oil droplet 4% density of oil 1% gravitational fiel
  13. June 2023, Paper 3 Turning points, Q01.1 (1 mark): Explain how the electrons that form the beam are emitted. [1 mark]
  14. June 2023, Paper 3 Turning points, Q01.2 (1 mark): Show that the maximum speed of the electrons in the beam is about 1.3 × 107 m s−1. [1 mark]
  15. June 2023, Paper 3 Turning points, Q01.4 (6 marks): In 1897, J J Thomson determined a value for the specific charge of an unknown particle. The unknown particle is now known to be the electron. Describe one metho
  16. June 2023, Paper 3 Turning points, Q02.1 (3 marks): Calculate the viscosity of the air between the plates. [3 marks] viscosity = N s m−2
  17. June 2023, Paper 3 Turning points, Q02.2 (3 marks): During the experiment, an electric field is produced between the plates and is adjusted until the oil drop is stationary. The electric field strength is 18.8 kV
  18. June 2022, Paper 3 Turning points, Q02.1 (1 mark): State and explain the sign of the charge on the oil droplet. [1 mark] The variable voltage supply is set to zero volts. The oil drop falls. The constant speed v
  19. June 2022, Paper 3 Turning points, Q02.2 (3 marks): Show that the mass m of the oil droplet is about 8 × 10−16 kg. [3 marks]
  20. June 2022, Paper 3 Turning points, Q02.3 (2 marks): The variable voltage supply is adjusted so that the oil droplet rises at a constant speed v2. The potential difference (pd) across the plates is V and the dista
  21. June 2022, Paper 3 Turning points, Q02.4 (3 marks): The following measurements are made for the droplet in Question 02.2 when it is rising at constant speed. V = 715 V v2 = 1.1 × 10−4 m s−1 The separation of the
  22. June 2022, Paper 3 Turning points, Q02.5 (3 marks): After Millikan published his results, it was found that he had used a value for the viscosity of air that was smaller than the actual value. Discuss the effect
  23. November 2021, Paper 3 Turning points, Q01.1 (4 marks): Explain how high-speed electrons are produced in the apparatus in Figure 1. In your answer you should: • name parts A and B • discuss the purposes of potential
  24. November 2020, Paper 3 Turning points, Q01.1 (2 marks): When correct connections are made to a high-voltage power supply, a cathode ray is produced. The cathode ray hits the centre of the fluorescent screen. Describe
  25. November 2020, Paper 3 Turning points, Q01.2 (1 mark): P and Q are metal plates that can be attached to a second power supply. In an experiment, a potential difference (pd) is applied across P and Q so that P is pos
  26. November 2020, Paper 3 Turning points, Q01.3 (3 marks): Changes are made to the apparatus so that the particles in the cathode ray travel with a greater speed as they pass between plates P and Q. Explain how the cath
  27. November 2020, Paper 3 Turning points, Q01.4 (2 marks): Using the apparatus in Figure 1, Thomson determined the specific charge of the particles in the cathode rays. Thomson compared this result with the specific cha
  28. June 2019, Paper 3 Turning points, Q01.1 (2 marks): Identify the forces acting on the stationary droplet. In your answer you should state the relationship between the forces. The upthrust on the droplet due to th
  29. June 2019, Paper 3 Turning points, Q01.2 (3 marks): The potential difference between the plates is changed to zero and the droplet falls at a terminal velocity of 1.0 × 10−4 m s−1. The density of the oil is 880 k
  30. June 2019, Paper 3 Turning points, Q01.3 (3 marks): The potential difference between the plates is restored to its initial value and the droplet becomes stationary. The charge on the droplet is −4.8 × 10−19 C. A
  31. June 2018, Paper 3 Turning points, Q01.1 (3 marks): Describe the process that releases the electrons emitted at the filament. [3 marks]
  32. June 2018, Paper 3 Turning points, Q01.2 (2 marks): Table 1 shows the data collected when determining the specific charge of the electron by the method shown in Figure 1. Table 1 potential difference V that accel
  33. June 2018, Paper 3 Turning points, Q01.3 (2 marks): Using data from Table 1, calculate a value for the specific charge of the electron. Give your answer to an appropriate number of significant figures. [2 marks]
  34. June 2018, Paper 3 Turning points, Q01.4 (2 marks): At the time when Thomson measured the specific charge of the particles in cathode rays, the largest specific charge known was that of the hydrogen ion. State ho
  35. June 2017, Paper 3 Turning points, Q01.1 (2 marks): Explain how this experiment led Crookes to conclude that cathode rays are particles and that these particles caused the movement of the paddle. [2 marks]
  36. June 2017, Paper 3 Turning points, Q01.2 (3 marks): Later experiments showed that cathode rays are electrons in motion. Explain how cathode rays are produced in a gas discharge tube. [3 marks]
  37. June 2017, Paper 3 Turning points, Q01.3 (2 marks): In a particular gas discharge tube, air molecules inside the tube are absorbed by the walls of the tube. Suggest the effect that this absorption may have on the
  38. June 2017, Paper 3 Turning points, Q03.1 (1 mark): What is the process by which electrons are produced in an electron gun? Tick () the correct box. [1 mark] Beta particle emission Electron diffraction Photoelec

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