Radioactive substances give out
radiation all of the time. There are three types of nuclear radiation:
alpha, beta and gamma. Alpha is the least penetrating, while gamma is
the most penetrating.
Radiation can be harmful, but it can also be useful. The uses of radiation include smoke detectors, paper-thickness gauges, treating cancer and sterilising medical equipment.
Radiation can be harmful, but it can also be useful. The uses of radiation include smoke detectors, paper-thickness gauges, treating cancer and sterilising medical equipment.
Types of radiation
Nuclear radiation comes from the nucleus of an atom. Substances that give out radiation are said to be radioactive. There are three types of nuclear radiation:- alpha
- beta
- gamma
The thicker the substance, the more the radiation is absorbed. The three types of radiation penetrate materials in different ways.
Penetrative properties of different types of radiation
Alpha radiation
Alpha radiation is the least penetrating. It can be stopped (or absorbed) by a sheet of paper.Beta radiation
Beta radiation can penetrate air and paper. It can be stopped by a thin sheet of aluminium.Gamma radiation
Gamma radiation is the most penetrating. Even small levels can penetrate air, paper or thin metal. Higher levels can only be stopped by many centimetres of lead, or many metres of concrete.Check your understanding by having a go at this animation. Click on each image of the rock to discover the reading on the radiation meter. Use the readings to confirm that the rock gives out beta radiation.
Uses of radiation
Ionisation
Nuclear radiation ionises materials. This changes atoms or molecules into charged particles.Uses of alpha radiation
Ionisation is useful for smoke detectors. Radioactive americium releases alpha radiation, which ionises the air inside the detector. Smoke from a fire absorbs alpha radiation, altering the ionisation and triggering the alarm.Uses of beta radiation
Beta radiation is used for tracers and monitoring the thickness of materials.Doctors may use radioactive chemicals called tracers for medical imaging. Certain chemicals concentrate in different damaged or diseased parts of the body, and the radiation concentrates with it. Radiation detectors placed outside the body detect the radiation emitted and, with the aid of computers, build up an image of the inside of the body.
Radiation is used in industry in detectors that monitor and control the thickness of materials such as paper, plastic and aluminium. The thicker the material, the more radiation is absorbed and the less radiation reaches the detector. It then sends signals to the equipment that adjusts the thickness of the material. Check your understanding of this by watching the simulation.