Uses & Hazards of Radiation (OCR GCSE Physics A (Gateway))

A student does an experiment with radioactive materials.

• He investigates how the activity of radiation changes with distance.

• In the experiment, the radiation moves from the radioactive source to a detector.

• He measures the counts per minute at the detector.

The table shows the results.

The student could not take an accurate reading at 0 cm.

Suggest a reason why.

i) Plot the results on the graph below.

Two points for 10 cm and 40 cm have been plotted for you.

Join the points with a smooth curve.

[2]

ii) Use the graph to estimate the count rate at 30 cm.

Answer = ......................... counts per minute

Higher Tier Only

 i) What pattern is shown by the results as the distance is increased from 20 to 40 cm?

[2]

ii) The student wants to find the count rate at 5 cm.

Estimate the count rate at a distance of 5 cm.

Answer = .......................... counts per minute [1]

The student considers the risks of doing experiments with radioactive sources.

He does experiments with two radioactive sources, A and B.

He writes down his conclusions about the sources in the table below.

Describe the difference in the risks for irradiation and contamination for A and B.

The table below shows information on radioactive isotopes.

A doctor injects a patient with isotope C to track blood flow through the Body.

Use the information to suggest why the doctor uses isotope C.

A doctor implants radioactive isotope A into a patient to treat a localised cancer which is a few mm in size. She intends to remove the isotope in a few weeks.

Use the data to suggest two reasons why the doctor uses isotope A.

A doctor wants to irradiate a tumour using gamma rays.

Why does the activity of the source need to be checked before it is used on a patient?

Nuclear radiation, such as gamma, is used to irradiate some fresh food to increase its ‘shelf-life’ and make it last longer.

Fresh herbs and spices are dried and irradiated with gamma rays.

Explain the difference between nuclear irradiation and nuclear contamination.

Explain how the gamma rays can increase the ‘shelf-life’ of herbs and spices to make them last longer.

Some people are worried about eating irradiated food.

Write down two concerns they may have about irradiated food.

1 ....................................................................................................... 2.......................................................................................................

Carbon is a common element. Carbon has two different isotopes called carbon-12 and carbon-14. Both of these isotopes have six protons in the nucleus.

i) Carbon-14 is radioactive and carbon-12 is not radioactive.

Explain why some isotopes are radioactive.

[1]

ii) Describe how the nucleus of carbon-12 is different to the nucleus of carbon-14.

[1]

Decay equations are used to show the type of emission from different radioactive elements.

i) Complete the decay equation for alpha emission.

[2]

ii) Complete the decay equation for beta emission.

[2]

iii) Complete the decay equation for gamma emission.

[2]

When a uranium-235 (U-235) nucleus absorbs a neutron, the nucleus splits into smaller parts.

This reaction is called nuclear fission.

State how many daughter nuclei are produced from the fission of one nucleus of U-235.

When a U-235 nucleus undergoes fission, neutrons are also emitted.

The neutrons may start a chain reaction.

Describe how a chain reaction occurs in nuclear fission.

You may draw a diagram to help with your answer.

Nuclear fusion occurs in the Sun.

Describe what happens during a nuclear fusion reaction.