Uses of Radiation (AQA GCSE Physics: Combined Science)
Revision Note
Author
Katie MExpertise
Physics
Uses of Radiation
- Radiation is used in a number of different ways, for example:
- Producing electricity through nuclear fission
- Medical procedures including diagnosis and treatment
- Testing material
- Determining the age of ancient artefacts
- Checking the thickness of materials
- Smoke detectors
- The properties of the different types of radiation determine which one is used in a particular application
Smoke Detectors & Alpha Particles
- Alpha particles are used in smoke detectors
- The alpha radiation will normally ionise the air within the detector, creating a current
- The alpha emitter is blocked when smoke enters the detector
- The alarm is triggered by a microchip when the sensor no longer detects alpha
In the diagram on the right, alpha particles are stopped by the smoke, preventing the flow of current and triggering the alarm
Worked example
Explain why is alpha radiation used in smoke detectors, and not beta or gamma radiation.
- Consider the different properties of alpha, beta and gamma:
- Alpha is the most weakly penetrating and strongest ioniser
- Beta and gamma have stronger penetrating power and weaker ionising power
- If beta or gamma radiation were used in this situation then they would pass straight through the smoke and the alarm would not go off
- Therefore, since alpha is absorbed by smoke, and beta and gamma are not, this makes it most suitable for use in a smoke detector
- Consider the different properties of alpha, beta and gamma:
Exam Tip
You do not need to know the different uses of the different types of radiation but you must be able to use your knowledge of the properties of the different types in order to determine which source is the most appropriate for a particular use.
If you are presented with an unfamiliar situation in your exam don’t panic! Just apply your understanding of alpha, beta and gamma radiation - the answer will be found among those three.
The classes I have taught this topic to at GCSE have found the idea of application questions quite intimidating. Application questions present you with an unfamiliar context, and you have to apply what you have learned about the physics to that specific situation. What I always say to my students is this:
There are 3 types of radiation to choose from, alpha, beta and gamma. The properties of each will either make them suitable or unsuitable for a particular job. If you get stuck on why a certain type of radiation is suitable, think about why the other types are not suitable. Why wouldn't you use alpha particles for determining the thickness of paper? Because alpha particles are stopped by paper, so the detector would detect nothing. Why wouldn't you use gamma radiation? Because all the gamma radiation will pass through the paper, so this would tell you nothing about the thickness of the paper. That brings you to, why is beta radiation used? Because some beta particles will pass through the paper, so the thickness of the paper can be determined by how many pass through to the detector.
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