The term “radiation” can refer to quite a few things and many of those things are fairly difficult and complex to understand. Let’s start with the basics:
For Kids: Definitions
Simply put, radiation is energy. This can take the form of waves or as the movement of particles. So what’s the difference?
Waves: If you and a friend hold opposite ends of a rope and you wiggle one end hard enough, your friend will feel it. This can also happen when the wiggling is fast enough to turn into sound, as in a tin can telephone. Both of these are waves, the difference is their speed. Waves are everywhere. You can see them on the ocean, they can travel electrically through wires and when they are fast enough, we see them as light. Light is a special kind of wave called an electromagnetic wave. Electromagnetic waves are experienced differently based on their length and speed. Long, slow waves are used for radio and television signals, as they get shorter and faster they become microwaves, then Infrared waves (heat), then visible light rays. As they continue to get shorter and faster, they become Ultraviolet rays (causing sunburn), X-rays, Gamma rays and Cosmic rays. All this talk of rays is where we get the word radiation (ray-diation).
Particles: There is another kind of ray made up of particles instead of waves. So instead of wiggles, instead tiny hunks of matter are being thrown across space, like little bullets. When these are pieces of an atom that are thrown off as the atom changes, they are called subatomic particles and they stand a good chance of causing changes in whatever they hit.
When scientists talk about radioactivity, they are talking about one form of radiation called ionizing radiation. This is important because whatever is exposed to this kind of radiation is changed by it. People can get burns, become sick and may get cancer if they get too much ionizing radiation. For this reason, scientists place radiation into three categories based on how easy it is to protect yourself:
- Alpha Radiation can be stopped by paper
- Beta Radiation can be stopped by thin metal
- Gamma Radiation can be stopped by thick metal, deep water or several feet of earth
For Kids: Discovering Radiation
Ionizing radiation is invisible, so special instruments are needed to find it. The most common are Gamma ray detectors such as a Geiger counter. Unfortunately, the most common detectors only show moderate to strong levels of radiation and not what’s causing it. They answer the question of “how much?” and not “what is it?”
For Kids: Discovering Hidden Radiation
There is another form of radiation which is much harder to find. Scientists call this low-level nuclear contamination. Instruments may detect tiny amounts of radiation and people may think they are safe, but depending on what the cause is, this kind of radiation can cause problems later on. What happens is that plants and animals will absorb certain kinds of radioactive particles and their bodies will treat then just like chemicals they are used to. The question of ”what is it” becomes very important.
- Iodine-131 replaces harmless Iodine in the thyroid gland
- Caesium-137 and Strontium-90 replace harmless Calcium in the bones and teeth
- Plutonium-239 replaces harmless Iron in the blood and bone marrow
These new building blocks are like tiny firecrackers waiting to go off at any time and each time one does, there is a risk that it will damage a cell enough to start cancer. It becomes very important to find out about amounts of these hidden sources of radiation.