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Medical physics: WJEC A‑Level Physics questions

Every WJEC A-Level Physics exam question on 4.B Medical physics, 2016–2025, with its mark scheme and examiner’s report.

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1,173 questions

  1. Q8(a)(i)

    Summer 2025 · Unit 4

    2 marks4.B Medical physics
    The whole paper ↗
    Summer 2025 Unit 4, question 8(a)(i): Calculate the operating voltage of the tube. [2]

  2. Q8(a)(ii)

    Summer 2025 · Unit 4

    1 mark4.B Medical physics
    The whole paper ↗
    Summer 2025 Unit 4, question 8(a)(ii): Draw on the above graph a spectrum for the same X-ray tube with a higher operating voltage. [1]

  3. Q8(a)(iii)

    Summer 2025 · Unit 4

    1 mark4.B Medical physics
    The whole paper ↗
    Summer 2025 Unit 4, question 8(a)(iii): State the major difference you would see in the spectrum if the X-ray machine used a different target material. [1]

  4. Q8(a)(iv)

    Summer 2025 · Unit 4

    2 marks4.B Medical physics
    The whole paper ↗
    Summer 2025 Unit 4, question 8(a)(iv): Describe how a CT scan differs from a conventional X-ray and justify why CT scans are not offered for the regular checking of patients. [2]

  5. Q8(b)(i)

    Summer 2025 · Unit 4

    2 marks4.B Medical physics
    The whole paper ↗
    Summer 2025 Unit 4, question 8(b)(i): Describe how the ultrasound pulses are produced. [2]

  6. Q8(b)(ii)

    Summer 2025 · Unit 4

    5 marks4.B Medical physics
    The whole paper ↗
    Summer 2025 Unit 4, question 8(b)(ii): The following table gives the density and velocity of ultrasound in air and skin. Medium Density / Velocity of Acoustic impedance / ultrasound / kg m–3 kg m–2 s

  7. Q8(c)(i)

    Summer 2025 · Unit 4

    2 marks4.B Medical physics
    The whole paper ↗
    Summer 2025 Unit 4, question 8(c)(i): State and explain two essential characteristics of a radioactive isotope used as a tracer in medicine. [2]

  8. Q8(c)(ii)

    Summer 2025 · Unit 4

    3 marks4.B Medical physics
    The whole paper ↗
    Summer 2025 Unit 4, question 8(c)(ii): The total volume of a patient’s blood was estimated using an injection of radioactive sodium in solution. The half-life of the radioactive sodium solution was 1

  9. Q8(d)

    Summer 2025 · Unit 4

    2 marks4.B Medical physics
    The whole paper ↗
    Summer 2025 Unit 4, question 8(d): In a magnetic resonance imaging scanner (MRI), large magnetic fields of the order of 1.5 T are used along with short pulses of radio waves. Calculate a suitable

  10. Q8(a)

    Summer 2024 · Unit 4

    4 marks4.B Medical physics
    The whole paper ↗
    Summer 2024 Unit 4, question 8(a): Sketch two graphs to show how the intensity of X-rays from an X-ray tube varies with wavelength for an X-ray tube operating at two different voltages, one at 30

  11. Q8(b)(i)

    Summer 2024 · Unit 4

    2 marks4.B Medical physics
    The whole paper ↗
    Summer 2024 Unit 4, question 8(b)(i): Ultrasound can be used to measure the speed of blood through an artery. If ultrasound of frequency 1.5 MHz travelling at an angle of 30° to the direction of blo

  12. Q8(b)(ii)

    Summer 2024 · Unit 4

    1 mark4.B Medical physics
    The whole paper ↗
    Summer 2024 Unit 4, question 8(b)(ii): Suggest why it is important for doctors to monitor the rate of blood flow in a patient. [1]

  13. Q8(c)(i)

    Summer 2024 · Unit 4

    3 marks4.B Medical physics
    The whole paper ↗
    Summer 2024 Unit 4, question 8(c)(i): A magnetic resonance scanner (MRI) can be used to detect tumours in a patient’s body. Describe how an MRI scanner works. [3]

  14. Q8(c)(ii)

    Summer 2024 · Unit 4

    2 marks4.B Medical physics
    The whole paper ↗
    Summer 2024 Unit 4, question 8(c)(ii): The MRI scanner has a magnetic field of 1.4 T. Determine the wavelength of electromagnetic radiation that should be used to detect the tumour. [2]

  15. Q8(d)(i)

    Summer 2024 · Unit 4

    2 marks4.B Medical physics
    The whole paper ↗
    Summer 2024 Unit 4, question 8(d)(i): PET scanners are often used to diagnose tumours in patients. Calculate the energy of the emitted gamma rays (mpositron = melectron = 0.000 549 u, 1 u = 931 MeV)

  16. Q8(d)(ii)

    Summer 2024 · Unit 4

    1 mark4.B Medical physics
    The whole paper ↗
    Summer 2024 Unit 4, question 8(d)(ii): Explain why PET scanners are not commonly found in smaller hospitals. [1]

  17. Q8(e)

    Summer 2024 · Unit 4

    5 marks4.B Medical physics
    The whole paper ↗
    Summer 2024 Unit 4, question 8(e): Doctors are concerned about the growth of an unborn baby and have the choice of the following imaging techniques. X-ray fluoroscopy ultrasound B-scan ultrasound

  18. Q8(a)(i)

    Summer 2023 · Unit 4

    2 marks4.B Medical physics
    The whole paper ↗
    Summer 2023 Unit 4, question 8(a)(i): State the main function of the heater and explain why there must be a vacuum between the heater and the tungsten target. [2]

  19. Q8(a)(ii)

    Summer 2023 · Unit 4

    2 marks4.B Medical physics
    The whole paper ↗
    Summer 2023 Unit 4, question 8(a)(ii): The electron beam has a current of 100 mA. Determine how many electrons arrive at the tungsten target per second. [2]

  20. Q8(a)(iii)

    Summer 2023 · Unit 4

    3 marks4.B Medical physics
    The whole paper ↗
    Summer 2023 Unit 4, question 8(a)(iii): Estimate the velocity of an electron in the X-ray tube as it hits the target. [3]
All 49 questions on Medical physics, as a list
  1. Summer 2025, Unit 4, Q8(a)(i) (2 marks): Calculate the operating voltage of the tube. [2]
  2. Summer 2025, Unit 4, Q8(a)(ii) (1 mark): Draw on the above graph a spectrum for the same X-ray tube with a higher operating voltage. [1]
  3. Summer 2025, Unit 4, Q8(a)(iii) (1 mark): State the major difference you would see in the spectrum if the X-ray machine used a different target material. [1]
  4. Summer 2025, Unit 4, Q8(a)(iv) (2 marks): Describe how a CT scan differs from a conventional X-ray and justify why CT scans are not offered for the regular checking of patients. [2]
  5. Summer 2025, Unit 4, Q8(b)(i) (2 marks): Describe how the ultrasound pulses are produced. [2]
  6. Summer 2025, Unit 4, Q8(b)(ii) (5 marks): The following table gives the density and velocity of ultrasound in air and skin. Medium Density / Velocity of Acoustic impedance / ultrasound / kg m–3 kg m–2 s
  7. Summer 2025, Unit 4, Q8(c)(i) (2 marks): State and explain two essential characteristics of a radioactive isotope used as a tracer in medicine. [2]
  8. Summer 2025, Unit 4, Q8(c)(ii) (3 marks): The total volume of a patient’s blood was estimated using an injection of radioactive sodium in solution. The half-life of the radioactive sodium solution was 1
  9. Summer 2025, Unit 4, Q8(d) (2 marks): In a magnetic resonance imaging scanner (MRI), large magnetic fields of the order of 1.5 T are used along with short pulses of radio waves. Calculate a suitable
  10. Summer 2024, Unit 4, Q8(a) (4 marks): Sketch two graphs to show how the intensity of X-rays from an X-ray tube varies with wavelength for an X-ray tube operating at two different voltages, one at 30
  11. Summer 2024, Unit 4, Q8(b)(i) (2 marks): Ultrasound can be used to measure the speed of blood through an artery. If ultrasound of frequency 1.5 MHz travelling at an angle of 30° to the direction of blo
  12. Summer 2024, Unit 4, Q8(b)(ii) (1 mark): Suggest why it is important for doctors to monitor the rate of blood flow in a patient. [1]
  13. Summer 2024, Unit 4, Q8(c)(i) (3 marks): A magnetic resonance scanner (MRI) can be used to detect tumours in a patient’s body. Describe how an MRI scanner works. [3]
  14. Summer 2024, Unit 4, Q8(c)(ii) (2 marks): The MRI scanner has a magnetic field of 1.4 T. Determine the wavelength of electromagnetic radiation that should be used to detect the tumour. [2]
  15. Summer 2024, Unit 4, Q8(d)(i) (2 marks): PET scanners are often used to diagnose tumours in patients. Calculate the energy of the emitted gamma rays (mpositron = melectron = 0.000 549 u, 1 u = 931 MeV)
  16. Summer 2024, Unit 4, Q8(d)(ii) (1 mark): Explain why PET scanners are not commonly found in smaller hospitals. [1]
  17. Summer 2024, Unit 4, Q8(e) (5 marks): Doctors are concerned about the growth of an unborn baby and have the choice of the following imaging techniques. X-ray fluoroscopy ultrasound B-scan ultrasound
  18. Summer 2023, Unit 4, Q8(a)(i) (2 marks): State the main function of the heater and explain why there must be a vacuum between the heater and the tungsten target. [2]
  19. Summer 2023, Unit 4, Q8(a)(ii) (2 marks): The electron beam has a current of 100 mA. Determine how many electrons arrive at the tungsten target per second. [2]
  20. Summer 2023, Unit 4, Q8(a)(iii) (3 marks): Estimate the velocity of an electron in the X-ray tube as it hits the target. [3]
  21. Summer 2023, Unit 4, Q8(a)(iv) (3 marks): Option B – Medical Physics Determine the minimum wavelength, λ min, of the X-rays produced by this tube. [3] (iv)
  22. Summer 2023, Unit 4, Q8(b)(i) (3 marks): An ultrasound probe can be used to study the speed of blood flow from the heart. Explain how the probe produces ultrasound and how the speed of blood flow can b
  23. Summer 2023, Unit 4, Q8(b)(ii) (2 marks): In measuring the speed of blood flow, the frequency of ultrasound used is 2.0 MHz and it travels through the blood at 1570 m s–1. A frequency shift of 0.23 kHz
  24. Summer 2023, Unit 4, Q8(c) (5 marks): Doctors are concerned that a patient is suffering from an overactive thyroid gland (hyperthyroidism). They have the choice of the following techniques to help d
  25. Summer 2019, Unit 4, Q7(a)(i) (3 marks): Discuss how the properties of X-rays make them suitable for medical imaging. [3]
  26. Summer 2019, Unit 4, Q7(a)(ii) (4 marks): An X-ray machine has an operating pd of 18 kV and a current of 12 mA. If only 0.5% of the power is converted into X-rays find: I. the velocity with which the el
  27. Summer 2019, Unit 4, Q7(b)(i) (2 marks): The intensity, I, of an ultrasound beam decreases with the thickness, x, of a material according to the equation: I = I0e−µx The half-value thickness, is the th
  28. Summer 2019, Unit 4, Q7(b)(ii) (3 marks): The half-value thickness of muscle for ultrasound of frequency 1.0 MHz is 2.7 cm. Determine the thickness of muscle required to reduce the intensity to 70 % of
  29. Summer 2019, Unit 4, Q7(c) (5 marks): A patient has a suspected heart murmur possibly caused by a problem with their aortic valve. You have the choice of the following forms of medical imaging avail
  30. Summer 2019, Unit 4, Q7(d)(i) (2 marks): When discussing radiation exposure, medical scientists will mention the absorbed dose, D, and the equivalent dose, H. Explain the difference between these two t
  31. Summer 2019, Unit 4, Q7(d)(ii) (1 mark): During treatment for a cancerous tumour using gamma radiation, a patient’s lungs received an equivalent dose of 4 mSv. If the weighting factor of lung tissue is
  32. Summer 2018, Unit 4, Q7(a)(i) (2 marks): Sketch a graph of intensity against wavelength for the resulting X-ray spectrum. Label the main features of this spectrum, including a value for the minimum wav
  33. Summer 2018, Unit 4, Q7(a)(ii) (2 marks): At the working potential difference the current in the tube is 120 mA and the efficiency of the X-ray machine is 0.7 %. Calculate the rate of production of heat
  34. Summer 2018, Unit 4, Q7(a)(iii) (3 marks): A metal plate of thickness 1.4 mm is used to reduce the intensity of the X-rays produced to 60 % of the incident intensity. If a second identical plate is now a
  35. Summer 2018, Unit 4, Q7(b)(i) (2 marks): Describe how the Doppler shift principle can be used to measure the speed of blood through an artery. [2]
  36. Summer 2018, Unit 4, Q7(b)(ii) (2 marks): Ultrasound of frequency 2 MHz was used to calculate the speed of blood and a Doppler shift of 200 Hz was detected. The measurement was taken at an angle of 40o
  37. Summer 2018, Unit 4, Q7(c)(i) (3 marks): Describe the properties of technetium–99m (Tc–99m) that make it such a good radioisotope in the effective diagnosis of medical problems. Justify your choice of
  38. Summer 2018, Unit 4, Q7(c)(ii) (3 marks): Explain clearly how a gamma camera is used to detect the gamma rays given off by a technetium–99m source. [3]
  39. Summer 2018, Unit 4, Q7(c)(iii) (3 marks): In positron emission tomography a positron annihilates an electron producing two photons of energy 0.511 MeV. By setting out your reasoning clearly, determine w
  40. Summer 2017, Unit 4, Q7(a)(i) (1 mark): State how fast moving electrons can produce X-rays. [1]
  41. Summer 2017, Unit 4, Q7(a)(ii) (2 marks): Determine the number of electrons arriving at the target every second. [2]
  42. Summer 2017, Unit 4, Q7(a)(iii) (3 marks): Calculate the acceleration of an electron in the X-ray tube as it travels towards the target. [3]
  43. Summer 2017, Unit 4, Q7(a)(iv) (2 marks): Explain how the photon energy and the intensity of the X-ray output can be increased. [2]
  44. Summer 2017, Unit 4, Q7(b) (2 marks): Give one advantage and one disadvantage of using CT scans compared with conventional X-ray imaging. [2]
  45. Summer 2017, Unit 4, Q7(c) (4 marks): The following table provides information relating to ultrasound in fat and muscle. Density / kg m–3 Speed / m s–1 Tissue 1.1 × 103 1.6 × 103 Muscle 0.8 × 103 1.
  46. Summer 2017, Unit 4, Q7(d)(i) (2 marks): Explain briefly the role played by the absorbed radio waves in the resonance process of MRI scans. [2]
  47. Summer 2017, Unit 4, Q7(d)(ii) (2 marks): In an MRI scanner radio waves of frequency 64 MHz are absorbed and cause hydrogen atoms to resonate in a magnetic field of 1.5 T. Determine the frequency of abs
  48. Summer 2017, Unit 4, Q7(e)(i) (1 mark): Alpha particles have a radiation weighting factor of 20 If a patient receives an absorbed dose of 55 mGy determine the dose equivalent received. [1]
  49. Summer 2017, Unit 4, Q7(e)(ii) (1 mark): State whether or not beta particles would have a weighting factor of 20, greater than 20 or less than 20 Justify your answer. [1]

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