1. 1
   A factory uses a radioactive source to control the thickness of aluminium foil as it passes continuously between the source and a detector on a production line, with the detector's reading used to adjust the rollers automatically.

   (a)

   The type of radiation used is stopped by only a few millimetres of aluminium. Which type of radiation is being used?

   [1 mark]

   • ABeta radiation
   • BAlpha radiation
   • CGamma radiation
   • DInfrared radiation

   (b)

   What is the nature of the radiation used in the factory's foil-thickness detector?

   [1 mark]

   • ATwo protons and two neutrons bound together
   • BA fast-moving electron
   • CA high-frequency electromagnetic wave
   • DA neutral particle with no mass

   (c)

   Explain why alpha radiation would not be suitable for this thickness-monitoring application, and why gamma radiation would also not be suitable.

   [2 marks]

   Total for question 1: 4 marks

2. 2
   A hospital uses gamma radiation from a sealed source to sterilise medical equipment before it is packaged, and a technician tests the penetrating ability of the radiation as part of routine safety checks.

   (a)

   A hospital uses gamma radiation to sterilise medical equipment before it is packaged. A technician wants to confirm that the radiation being used is indeed gamma radiation by testing its penetrating ability. Which observation would confirm this is gamma radiation rather than alpha or beta?

   [1 mark]

   • AThe radiation is completely stopped by a few millimetres of aluminium
   • BThe radiation is completely stopped by a single sheet of paper
   • CThe radiation is only significantly reduced by several centimetres of a dense material such as lead
   • DThe radiation cannot travel through air at all

   (b)

   Which statement correctly describes the ionising effect of gamma radiation compared with alpha and beta radiation?

   [1 mark]

   • AGamma radiation and alpha radiation have exactly the same ionising effect
   • BGamma radiation has the strongest ionising effect of the three
   • CGamma radiation has no ionising effect at all
   • DGamma radiation has the weakest ionising effect of the three

   (c)

   Explain why gamma radiation has a weaker ionising effect than alpha radiation, with reference to the electric charge and kinetic energy of each type of radiation.

   [2 marks]

   Total for question 2: 4 marks

3. 3
   A historical experiment passes a beam of radiation from a radioactive source between two oppositely charged parallel plates, with the positive plate on the left and the negative plate on the right, and observes how each part of the beam behaves.

   (a)

   Three separate components of the beam are observed: one deflects towards the negative plate, one deflects towards the positive plate, and one passes straight through undeflected. Identify each of the three types of radiation and explain the reasoning behind each identification.

   [3 marks]

   (b)

   The same three components of the beam are then passed through a strong magnetic field directed into the page, instead of the electric field. Describe and explain the differences in behaviour you would expect to see for the three types of radiation in this magnetic field, referring to their charge and relative mass.

   [4 marks]

   Total for question 3: 7 marks

4. 4
   A company that manufactures household products uses three different radioactive sources, each emitting a different type of nuclear radiation, for a smoke alarm, a food irradiation unit and an industrial thickness gauge respectively.

   (a)

   A company that manufactures smoke alarms, food irradiation equipment and industrial thickness gauges uses three different radioactive sources, each emitting a different type of nuclear radiation, for these three different applications. Describe the nature (composition or type), relative ionising effect and relative penetrating ability of alpha, beta and gamma radiation, and explain which type of radiation would be most suitable for use in a household smoke alarm, given that the radiation must ionise air particles inside a small detection chamber but must not be able to escape and harm people in the house.

   [6 marks]

   (b)

   The company's food irradiation unit uses gamma radiation to kill bacteria on packaged food without significantly heating it, and the industrial thickness gauge uses beta radiation to monitor material thickness on a production line. Explain why gamma radiation is chosen for food irradiation rather than alpha or beta radiation, and explain why beta radiation, rather than alpha or gamma, is chosen for the thickness gauge, referring to the penetrating ability of each type of radiation in your answer.

   [6 marks]

   Total for question 4: 12 marks

End of questions