Radioactive decay and nuclear radiation

A teacher investigated the radiation emitted by two different radioactive sources, A and B.

Figure 14 shows a radiation detector positioned near one of the radioactive sources.

The teacher measured the count rate at different distances for each radioactive source.

Figure 15 shows the results.

Explain how Figure 15 shows that Source A only emits alpha radiation.

Figure 15 can not be used to determine if Source B emits beta radiation or gamma radiation.

Explain how an absorbing material could be used to show which type of radiation is emitted by Source B.

The teacher took safety precautions during the experiment.

Suggest one safety precaution the teacher would have taken to reduce the radiation dose the teacher received.

Suggest one safety precaution that the teacher would have taken to avoid becoming contaminated.

Figure 16 shows how the number of atoms of a radioactive element in a sample varied with time.

Activity is the rate at which a source of unstable nuclei decays.

Determine the activity of the radioactive sample at 300 seconds.

Give the unit.

Radioactive isotopes emit different types of nuclear radiation.

What does an alpha particle consist of?

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What is a beta particle?

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A krypton (Kr) nucleus decays into a rubidium (Rb) nucleus by emitting a beta particle.

What is the correct equation for this decay?

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Figure 5 shows an experiment to demonstrate how alpha, beta and gamma radiation penetrate different materials.

The experiment takes place in a vacuum.

Three different materials are used:

• a sheet of paper

• a 0.5 cm thick sheet of aluminium

a 10 cm block of lead.

Each material is placed one at a time between the radioactive source and the GM tube.

The GM tube and counter show whether the material has stopped the radiation.

Complete Table 1 to show how alpha, beta and gamma radiation penetrate the materials in Figure 5.

Use the words Yes and No.

Part of Table 1 has been completed for you.

Alpha, beta and gamma radiation have different ionising powers.

Draw one line from each radiation type to the correct ionising power.

Some sources of background radiation are natural and other sources are man-made.

Which of the following is a man-made source of background radiation?

Tick (✓) one box.

The average background radiation dose per year in the UK is 2.0 millisieverts.

A dental X-ray gives a patient a radiation dose of 0.005 millisieverts.

Calculate how many dental X-rays would be the same as the average background radiation dose per year.

Atoms of different elements have different properties.

Which of the following is the same for all atoms of the same element?

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Which of the following is different for isotopes of the same element?

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A nucleus emits radiation.

Figure 7 shows how the mass number and the atomic number change.

The nucleus is labelled D.

Which type of radiation is emitted when nucleus D decays?

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Nucleus E also emits radiation.

Figure 8 shows how the mass number and the atomic number change for nucleus E.

Which type of radiation is emitted when nucleus E decays?

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Beta radiation can be used to monitor the thickness of paper during production.

Figure 9 shows how the radiation is used.

The computer uses information from the radiation detector to change the size of the gap between the rollers.

Complete the sentences.

Choose answers from the box.

Each answer can be used once, more than once or not at all.

The thickness of the paper between the beta source and the detector increases.

This is because the amount of radiation absorbed by the paper

All radioactive elements have a half-life.

What is meant by ‘half-life’?

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Why should the radiation source used in Figure 9 have a long half-life?

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A teacher used a Geiger-Muller tube and counter to measure the number of counts in 60 seconds for a radioactive rock.

The counter recorded 819 counts in 60 seconds. The background radiation count rate was 0.30 counts per second.

Calculate the count rate for the rock.

A householder is worried about the radiation emitted by the granite worktop in his kitchen.

1 kg of granite has an activity of 1250 Bq. The kitchen worktop has a mass of 180 kg.

Calculate the activity of the kitchen worktop in Bq.

The average total radiation dose per year in the UK is 2.0 millisieverts.

Table 2 shows the effects of radiation dose on the human body.

The average radiation dose from the granite worktop is 0.003 millisieverts per day.

Explain why the householder should not be concerned about his yearly radiation dose from the granite worktop.

One year is 365 days.

Bananas are a source of background radiation. Some people think that the unit of radiation dose should be changed from sieverts to Banana Equivalent Dose.

Suggest one reason why the Banana Equivalent Dose may help the public be more aware of radiation risks.

A teacher used a Geiger-Muller tube and counter to measure the number of counts in 60 seconds for a radioactive rock.

The counter recorded 819 counts in 60 seconds. The background radiation count rate was 0.30 counts per second.

Calculate the count rate for the rock.

A householder is worried about the radiation emitted by the granite worktop in his kitchen.

1 kg of granite has an activity of 1250 Bq. The kitchen worktop has a mass of 180 kg.

Calculate the activity of the kitchen worktop in Bq.

The average total radiation dose per year in the UK is 2.0 millisieverts.

Table 1 shows the effects of radiation dose on the human body.

The average radiation dose from the granite worktop is 0.003 millisieverts per day.

Explain why the householder should not be concerned about his yearly radiation dose from the granite worktop.

One year is 365 days.

Bananas are a source of background radiation. Some people think that the unit of radiation dose should be changed from sieverts to Banana Equivalent Dose.

Suggest one reason why the Banana Equivalent Dose may help the public be more aware of radiation risks.

Smoke alarms contain an alpha radiation source and a radiation detector.

Figure 9 shows part of the inside of a smoke alarm.

The smoke alarm stays off while alpha radiation reaches the detector.

Why does the alarm switch on when smoke particles enter the plastic casing?

Why is it safe to use a source of alpha radiation in a house?

The smoke alarm would not work with a radiation source that emits beta or gamma radiation.

Explain why.

Figure 10 shows how the count rate detected from the radiation source in the smoke alarm changes with time.

Figure 10

The smoke alarm switches on when the count rate falls to 80 counts per second.

Explain why the radiation source inside the smoke alarm should have a long half-life.

Figure 11 shows a patient who has been injected with a radioactive source for medical diagnosis.

Figure 11

Explain the ideal properties of a radioactive source for use in medical diagnosis.