Types of nuclear radiationEdexcel International A Level Physics: Subtopic test

1. 1
   A student investigates a radioactive source in a school laboratory using a Geiger–Müller tube connected to a counter. Before bringing the source out of its store, she records 120 counts in 10 minutes. With the source placed 5 cm from the tube she then records 1890 counts in 5.0 minutes.

   (a)

   Which of the following is a natural source of background radiation?

   [1 mark]

   • AVisible light from the Sun
   • BMicrowaves from the laboratory
   • CRadon gas released from rocks
   • DRadio waves from a transmitter

   (b)

   What is the corrected count rate due to the source alone?

   [1 mark]

   • A378 counts per minute
   • B366 counts per minute
   • C390 counts per minute
   • D1770 counts per minute

   (c)

   Explain why the student measures the background count over a long period and what she does with it.

   [2 marks]

   Total for question 1: 4 marks

2. 2
   A technician is testing two unlabelled sources, X and Y, using a Geiger–Müller tube about 2 cm away and subtracting the background count rate each time. For source X, the corrected count rate falls to zero when a single sheet of paper is placed in front of the tube. For source Y, a sheet of paper makes no difference, but the corrected count rate falls to zero when a 4 mm thick aluminium plate is placed in front of the tube.

   (a)

   Which type of radiation is emitted by source X?

   [1 mark]

   • AGamma radiation
   • BBeta-minus particles
   • CNeutrinos
   • DAlpha particles

   (b)

   Which statement correctly compares the radiation from X with that from Y?

   [1 mark]

   • AThe radiation from X is more strongly ionising and has the shorter range in air
   • BThe radiation from X is more strongly ionising and has the longer range in air
   • CThe radiation from X is less strongly ionising and has the shorter range in air
   • DThe radiation from X and Y is equally ionising and has the same range in air

   (c)

   Explain why the radiation from source X is stopped by paper but the radiation from source Y is not.

   [2 marks]

   Total for question 2: 4 marks

3. 3
   Radium-226 (proton number 88) is a naturally occurring alpha emitter that decays to an isotope of radon (Rn). Carbon-14 (proton number 6) is a beta-minus emitter that is used in radiocarbon dating and decays to an isotope of nitrogen (N).

   (a)

   Complete the nuclear equation for the alpha decay of radium-226: $^{226}_{88}\text{Ra} \rightarrow \ ?\ + \ ?$

   [3 marks]

   (b)

   Write the nuclear equation for the beta-minus decay of carbon-14, and explain what happens inside the nucleus so that the proton number increases by one.

   [4 marks]

   Total for question 3: 7 marks

4. 4
   A class investigates the absorption of gamma radiation by lead, using a gamma source, a Geiger–Müller tube and counter, and a set of lead sheets of different thicknesses. The laboratory background count rate is about 20 counts per minute.

   (a)

   Describe how the class should carry out the investigation, including how they make the results reliable and how they keep themselves safe.

   [6 marks]

   (b)

   The corrected count rates were 640 counts per minute with no lead, 320 counts per minute with 8.0 mm of lead and 160 counts per minute with 16.0 mm of lead. Use these results to deduce how the lead absorbs the radiation, predict the corrected count rate for 20.0 mm of lead, and explain how this differs from the absorption of alpha particles.

   [6 marks]

   Total for question 4: 12 marks

End of questions