Practice practical questions - Radioactivity
You will complete eight Practical Activity Groups (PAGs) if you are studying GCSE Physics, and sixteen if you are studying GCSE Combined Science (six of these are in Physics). You could be asked questions about the apparatus, methods, safety precautions, results, analysis and evaluation of these experiments.
There are two PAGs in the Waves in matter section:
- P4 Measuring waves, eg use a ripple tank to measure the speed, frequency and wavelength of a wave.
- P8 Interactions of waves, eg investigate the reflection of light off a plane mirror and the refraction of light through prisms.
Learn about practicals with Dr Alex Lathbridge
Listen to the full series on BBC Sounds.
Dr Alex Lathbridge answers questions about practicals.
Sample question 1 - Foundation
Question
Describe how to handle radioactive materials safely. [2 marks]
OCR Gateway Science, GCE Physics, Paper B751, June 2013.
Any two from:
- wear protective clothing
- use tongs/keep your distance/stand a safe distance away
- short exposure time
- use a shield/lead lined containers
- direct away from people
Sample question 2 - Foundation
Question
Matt experiments with radioactive materials.
He investigates how the activity of radiation changes with distance.
The radiation moves from the source to a detector.
He measures the counts per minute from a radioactive source.
The table shows the results from the experiment.
| Distance between the source and the detector (cm) | Count rate (counts per minute) |
| 10 | 1,000 |
| 20 | 240 |
| 40 | 60 |
| 80 | 20 |
| Distance between the source and the detector (cm) | 10 |
|---|---|
| Count rate (counts per minute) | 1,000 |
| Distance between the source and the detector (cm) | 20 |
|---|---|
| Count rate (counts per minute) | 240 |
| Distance between the source and the detector (cm) | 40 |
|---|---|
| Count rate (counts per minute) | 60 |
| Distance between the source and the detector (cm) | 80 |
|---|---|
| Count rate (counts per minute) | 20 |
a) Matt could not take an accurate reading at 0 cm. Suggest a reason why. [1 mark]
b) What pattern is shown by the results as the distance is increased from 20 cm to 40 cm? [2 marks]
OCR Gateway Science, GCE Physics, Paper J249, 2016.
a) The reading would be very high.
b) The activity decreases by a factor of 4.
Sample question 3 - Higher
Question
Matt experiments with radioactive materials.
He investigates how the activity of radiation changes with distance.
The radiation moves from the source to the detector.
He measures the counts per minute from a radioactive source.
The table shows the results from the experiment.
| Distance between the source and detector (cm) | Count rate (counts per minute) |
| 10 | 1,024 |
| 20 | 256 |
| 40 | 64 |
| 80 | 16 |
| Distance between the source and detector (cm) | 10 |
|---|---|
| Count rate (counts per minute) | 1,024 |
| Distance between the source and detector (cm) | 20 |
|---|---|
| Count rate (counts per minute) | 256 |
| Distance between the source and detector (cm) | 40 |
|---|---|
| Count rate (counts per minute) | 64 |
| Distance between the source and detector (cm) | 80 |
|---|---|
| Count rate (counts per minute) | 16 |
Describe using the data in the table how the count rate changes as the detector is moved away from the source. [2 marks]
OCR Gateway Science, GCE Physics, Paper J249, 2016 - Higher.
- as the distance doubles the count rate per minute is reduced by more than half
but
- as the distance doubles the count rate is 4 × less/count rate is inversely proportional to the square of the distance/as distance triples activity is 9 × less
Sample question 4 - Higher
Question
Matt experiments with radioactive materials.
He investigates how the activity of radiation changes with distance.
The radiation moves from the source to the detector.
He measures the counts per minute from a radioactive source.
His results are in the table below.
| Distance between the source and the detector (cm) | Count rate (counts per minute) |
| 10 | 1,024 |
| 20 | 256 |
| 40 | 64 |
| 80 | 16 |
| 160 | 6 |
| 320 | 0 |
| Distance between the source and the detector (cm) | 10 |
|---|---|
| Count rate (counts per minute) | 1,024 |
| Distance between the source and the detector (cm) | 20 |
|---|---|
| Count rate (counts per minute) | 256 |
| Distance between the source and the detector (cm) | 40 |
|---|---|
| Count rate (counts per minute) | 64 |
| Distance between the source and the detector (cm) | 80 |
|---|---|
| Count rate (counts per minute) | 16 |
| Distance between the source and the detector (cm) | 160 |
|---|---|
| Count rate (counts per minute) | 6 |
| Distance between the source and the detector (cm) | 320 |
|---|---|
| Count rate (counts per minute) | 0 |
As the distance is increased to 160 cm and 320 cm the results do not follow the same pattern as the other results.
What do you think these results should have been? Explain the anomalies in the last two results. [3 marks]
OCR Gateway Science, GCE Physics, Paper J249, 2016 - Higher.
- if the pattern was followed, 160 cm (ideally) should be 4 ÷ 320 cm (ideally) should be 1
- radiation/activity is random
- randomness is amplified at low readings
