Background radiation

Figure 12 is a diagram representing an atom.

Write the names of the particles X, Y and Z on the lines next to each letter in Figure 12.

The nucleus of a different atom emits a gamma ray.

What happens to the number of particles in the nucleus?

A teacher demonstrates a radioactivity experiment to a class of students.

The teacher places a radioactive source in front of a radiation detector.

State one safety precaution the teacher should take.

The teacher uses the detector to measure the activity of the source several times.

Figure 13 shows the results.

The teacher tells the class that radioactive decay is random.

State how the data in Figure 13 supports this statement.

Calculate the mean of the four measurements in Figure 13.

The teacher moves the radiation detector to different distances from the radioactive source.

The teacher determines the mean detector reading at each distance from the source.

The teacher plots the results on graph paper, as shown in Figure 14.

The source emits alpha radiation only.

Explain how the graph in Figure 14 shows that the source only emits alpha radiation.

Give a reason why the mean detector reading in Figure 14 does not fall to zero in this experiment.

An electron has a charge of –1.

The charge on an alpha particle is

Alpha, beta and gamma are all ionising radiations.

Give the meaning of the term ionising.

A teacher determines the background radiation count rate in a laboratory.

Explain how to determine a value for the background radiation count rate.

The teacher now investigates the absorption of beta radiation by different thicknesses of aluminium.

The apparatus available is

• a source of beta radiation

• a Geiger–Müller (G-M) tube and counter

• 10 pieces of aluminium, each 0.5 mm thick

• a metre rule.

Sketch a labelled diagram showing the positions of the apparatus when the measurements are being taken.

Give the independent variable in this investigation.

Name a quantity that must be kept constant during the investigation.

Strontium-90 is the source of beta minus radiation in this investigation.

Complete the nuclear equation for this emission of beta minus radiation.

This question is about radioactivity.

Alpha (α), beta (β) and gamma (γ) are three types of radioactive emissions.

Which statement describes all of these radioactive emissions?

Fluorine-19 is a stable isotope of the element fluorine.

The element fluorine also has several radioactive isotopes.

Describe one similarity and one difference between the numbers of particles in one nucleus of fluorine-19 and one nucleus of a radioactive isotope of fluorine.

Figure 14 shows a Geiger-Muller (G-M) tube attached to a counter. The G-M tube is used to measure the activity of a source of beta (β) radiation. There is an aluminium sheet between the beta source and the G-M tube. The counter is switched on and after 1 minute shows a count of 268.

The aluminium sheet is taken away. The counter is reset to zero and then switched on again. A new count is taken for 1 minute.

Explain why the new count is greater than 268.

The beta source is then also taken away. The counter is reset to zero and switched on again. A new count is taken for 1 minute.

Give a reason why there would now be a reading on the counter.

State the SI unit for the activity of a radioactive source.

*(d) Exposing people to radioactive sources can be dangerous.

Describe the dangers of exposure to radioactive sources and what can be done to protect hospital staff when they are working with radioactive sources.

This question is about radioactivity.

Alpha (α), beta (β) and gamma (γ) are three types of radioactive emissions.

Which statement describes all of these radioactive emissions?

Fluorine-19 is a stable isotope of the element fluorine.

The element fluorine also has several radioactive isotopes.

Describe one similarity and one difference between the numbers of particles in one nucleus of fluorine-19 and one nucleus of a radioactive isotope of fluorine.

Figure 3 shows a Geiger-Muller (G-M) tube attached to a counter. The G-M tube is used to measure the activity of a source of beta (β) radiation. There is an aluminium sheet between the beta source and the G-M tube. The counter is switched on and after 1 minute shows a count of 268.

The aluminium sheet is taken away. The counter is reset to zero and then switched on again. A new count is taken for 1 minute.

Explain why the new count is greater than 268.

The beta source is then also taken away. The counter is reset to zero and switched on again. A new count is taken for 1 minute.

Give a reason why there would now be a reading on the counter.

State the SI unit for the activity of a radioactive source.

Radium-223 is a radioactive substance.

Radium-223 is an alpha emitter.

The half-life of radium-223 is 11 days.

A radioactive source contains 1.7 × 10²³ nuclei of radium-223.

Calculate the number of radium-223 nuclei remaining in the source after a time of 33 days.

Carbon‑13 and carbon‑14 are isotopes of carbon.

Nuclei of carbon‑13 and carbon‑14 can be represented by these symbols

13 14

Complete the table for an atom of carbon‑13 and an atom of carbon‑14.

State the name of an instrument that can be used to measure radioactivity.

State two sources of background radiation.

Carbon‑14 is radioactive and has a half‑life of 5 700 years.

The number of radioactive carbon‑14 atoms in a very old piece of wood is found to have decreased from 1 000 000 to 125 000.

Determine the age of the piece of wood.

Carbon‑14 decays into nitrogen‑14.

The symbol for nitrogen‑14 is¹⁴₇N

Explain what happens in a carbon‑14 nucleus when it decays to a nitrogen‑14 nucleus.