Radiation is rays of particles or waves, traveling from a source from one place to another at the speed of light.
Radiation is energy that has an electric field and a magnetic field associated with it and has wave-like properties. You could also call radiation “electromagnetic waves”.
Does radiation make things radioactive?
Exposure to radiation does not immediately make a person radioactive. Neutron radiation is the only type of radiation that can directly cause other material to become radioactive, and it is generally only found inside nuclear reactors or during a nuclear detonation.
The radiation given off by radioactive substances includes alpha rays, beta rays, and gamma rays. Light, heat, and radio waves are examples of electromagnetic radiation.
Types of radiation
Other forms of radiation include cosmic rays which reach Earth from space and solar radiation which reaches us from the Sun. The kinds of radiation fall into a few general categories: electromagnetic radiation, mechanical radiation, nuclear radiation, and cosmic rays.
Electromagnetic radiation comes from atoms, the building blocks of all matter. Some of the particles that make up atoms have an electric charge.
The motion of these charged particles produces energy that can be described as traveling as waves. These waves combine electricity and magnetism. They can travel through space, like in outer space.
They can also travel through the air and even solid substances, such as glass. Through space, the waves travel at a speed of about 186,282 miles per second (299,792 kilometers per second).
Peaks and valleys
Like all waves, electromagnetic waves have peaks and valleys. The distance from the peak of one wave to the peak of the next wave is called a wavelength. Different kinds of electromagnetic waves have different wavelengths.
From longest to shortest wavelength, the types of electromagnetic radiation are radio waves, infrared rays, visible light, ultraviolet rays, X-rays, and gamma rays.
People use radio waves for sending signals, including television and radio broadcasts. Cooks use short radio waves called microwaves to cook food in microwave ovens. Warm objects give off infrared radiation, or heat.
The sun heats Earth with infrared radiation. The human eye can see all the wavelengths of visible light. We see different wavelengths of visible light as different colors.
The skin uses ultraviolet radiation to make a nutrient called vitamin D. Doctors use X-rays to take a picture of something inside an object, such as bones inside the body. Medicine uses gamma rays to kill cancer cells.
The shorter the wavelength, the more energy the radiation carries. The types with the most energy—ultraviolet radiation, X-rays, and gamma rays—can be harmful to the body.
Unlike electromagnetic radiation, mechanical radiation cannot travel through space. It can travel only through a substance, such as air, water, or solid objects.
Sound
A common example of mechanical radiation is sound. Sound is produced by the back-and-forth motion of a vibrating object. This motion produces sound waves that travel away from the object.
Sound travels more slowly than light does. This is why during a storm, the sound of thunder follows a flash of lightning.
An earthquake produces another form of mechanical radiation. The shock waves created by earthquakes travel through Earth and cause the ground to shake.
Nuclear radiation comes from the nucleus, or center, of atoms. It is produced when the nucleus changes in some way. The nucleus of some types of atoms is unstable.
An unstable nucleus can naturally change into another type of nucleus. When it does this, it shoots off nuclear radiation in the form of small particles or gamma rays. Scientists call atoms that give off radiation in this way radioactive.
Nuclear radiation carries a lot of energy, so it can be dangerous. Cosmic rays consist of tiny parts of atoms that speed through outer space. Cosmic rays can originate from the sun, but most originate from farther away in the galaxy.
Some cosmic rays travel almost at the speed of light. Because they move so fast, they have very high energy. Scientists study cosmic rays to learn more about the makeup of the galaxy.
