Uses of nuclear radiation (AQA GCSE Physics): Revision Notes
Uses of nuclear radiation
Nuclear radiation has many practical applications in everyday life. Each type of radiation - alpha particles, beta particles, and gamma-rays - is useful for different purposes because of their unique properties.
Medical and industrial uses of gamma-rays
Gamma-rays are the most penetrating type of radiation. This makes them very useful in hospitals and industry.
Cancer treatment
Doctors can aim beams of gamma-rays directly at cancer tumours. The radiation damages the cancer cells and destroys them. This helps patients fight cancer without needing surgery.
Gamma radiation therapy is a precise treatment that can target specific areas of the body while minimising damage to healthy surrounding tissue.
Sterilising medical equipment
Gamma-rays can kill bacteria and germs on medical instruments made from plastic. This is better than using heat, which would melt plastic equipment. The radiation makes everything completely sterile and safe to use.
Medical diagnosis
Doctors inject patients with a radioactive tracer that gives off gamma-rays. The tracer travels around the body and collects in areas where cells are growing unusually fast. A special camera detects the gamma-rays and shows doctors exactly where problems might be.
The radioactive tracers used in medical diagnosis contain very small amounts of radiation that are safe for patients and decay quickly in the body.
Food preservation
Food companies use gamma-rays to kill harmful microbes in food. This helps food last much longer without going bad. The food doesn't become radioactive - it just stays fresh for longer.
Smoke detectors in homes
Smoke alarms work by using a small amount of americium-241, which gives off alpha particles.
How smoke alarms work
The detector contains an alpha source that constantly releases alpha particles. These particles create a small electric current as they move through the air between two metal plates. When smoke enters the detector, it absorbs some of the alpha particles. This makes the current drop, which triggers the alarm to sound.
Alpha particles are perfect for this job because they are easily stopped by smoke particles but don't travel far enough to be dangerous to people in the house.
Quality control in paper manufacturing
Factories use beta particles to make sure paper comes out the right thickness.
The thickness control system
A beta radiation source is placed on one side of the paper as it's being made. A detector sits on the other side. If the paper becomes too thick, fewer beta particles get through to the detector. If it's too thin, more particles get through.
The detector sends signals to machines that automatically adjust the rollers. This keeps the paper at exactly the right thickness.
Worked Example: Paper Thickness Control Process
Step 1: Beta source emits particles towards detector
Step 2: Paper passes between source and detector
Step 3: Detector measures how many particles get through
Step 4: If too few particles = paper too thick → rollers adjust to make thinner
Step 5: If too many particles = paper too thin → rollers adjust to make thicker
Why beta particles work best
Beta particles are ideal for this because they can pass through thin paper but are stopped by thicker paper. Alpha particles wouldn't get through any paper at all. Gamma-rays would go through everything, making them useless for measuring small changes in thickness.
The choice of radiation type is critical - alpha particles are too weak, gamma-rays are too strong, but beta particles have just the right penetrating power for measuring paper thickness.
Key Points to Remember:
- Gamma-rays are used in medicine because they can penetrate deep into the body and kill cancer cells
- Alpha particles work perfectly in smoke alarms because smoke easily absorbs them
- Beta particles are ideal for controlling paper thickness because they have medium penetrating power
- Each type of radiation is chosen for specific jobs based on how well it can penetrate different materials
- These uses of radiation are safe because the amounts used are very small and carefully controlled