Uses of nuclear radiation (AQA GCSE Physics Combined Science): Revision Notes
Uses of nuclear radiation
Nuclear radiation has many practical uses in everyday life. The type of radiation chosen depends on its properties - how well it can penetrate through different materials.
Medical uses of gamma-rays
Gamma-rays are very useful in hospitals because they can pass through the human body easily.
Treating cancer
- Gamma-ray beams can be aimed directly at cancer cells to destroy them
- The high-energy radiation damages the cancer cells and kills them
- Doctors can focus the beams precisely on tumours
Gamma-ray cancer treatment works because cancer cells are often more sensitive to radiation damage than healthy cells, allowing doctors to target tumours while minimising harm to surrounding tissue.
Making medical equipment sterile
- Gamma-rays kill all germs and bacteria on surgical instruments
- This works even on plastic tools that would melt if heated for sterilisation
- The equipment stays completely sterile and safe to use
Finding cancer in the body
- Doctors inject a special radioactive substance called a tracer into patients
- Cancer cells absorb more of this tracer than healthy cells
- A special camera detects where the tracer has collected, showing where cancer might be growing
Keeping food fresh longer
- Food can be treated with gamma-rays to kill harmful bacteria
- This makes food last much longer without going off
- The food doesn't become radioactive - it's perfectly safe to eat
Despite common misconceptions, food treated with gamma-rays does not become radioactive. The radiation kills bacteria but does not change the food's chemical structure in harmful ways.
How smoke alarms work
Smoke alarms use alpha particles from a radioactive source called americium-241.
How Smoke Detection Works: Step-by-Step Process
Step 1: Normal operation
- Alpha particles from the source travel across a small gap in the detector
- These particles knock electrons off air molecules, creating an electric current
Step 2: Smoke enters the alarm
- Smoke particles absorb the alpha particles
- Fewer particles reach the detector
Step 3: Alarm activation
- With reduced particles, the current drops
- This change triggers the alarm to sound
Why alpha particles are perfect for this job
- Alpha particles have a very short range in air
- They are easily stopped by smoke particles
- They don't travel far enough to be dangerous to people in the house
- The americium-241 source gives off a steady stream of alpha particles
Controlling paper thickness in factories
Paper mills use beta particles to check that paper is the right thickness as it's being made.
Paper Thickness Control System: How It Works
Step 1: Setup
- A beta radiation source is placed on one side of the moving paper
- A detector sits on the other side to measure radiation levels
Step 2: Continuous monitoring
- If the paper gets thicker → fewer beta particles reach the detector
- If the paper gets thinner → more beta particles get through
Step 3: Automatic adjustment
- Machines automatically adjust the rollers to keep thickness constant
Why beta particles are chosen
The choice of radiation type is critical for this application:
- Alpha particles wouldn't work because they can't penetrate paper at all
- Gamma-rays wouldn't work because they pass through paper too easily - small thickness changes wouldn't affect the amount getting through
- Beta particles are just right - they are partially absorbed by paper, so thickness changes can be easily detected
Key Points to Remember:
- Gamma-rays are used in medicine because they penetrate deeply and can kill cancer cells or sterilise equipment
- Alpha particles work perfectly in smoke alarms because they're easily absorbed by smoke but have a short range
- Beta particles are ideal for measuring paper thickness because they are partially absorbed
- The choice of radiation type depends on how well it can penetrate the material being used
- All these uses rely on the different penetrating powers of alpha, beta and gamma radiation