Types of Electromagnetic RadiationThere are waves of energy and light moving all around us in the form of TV and audio transmissions, gamma radiation from space, and heat in the atmosphere. Scientists call them all electromagnetic radiation. The waves of energy are called electromagnetic (EM) because they have oscillating electric and magnetic fields. Scientists classify them by their frequency or wavelength, going from high to low frequency (short to long wavelength). For a wave with a high frequency, it has a lot of energy, so it could be a gamma ray or x-ray. If it has low frequency, it has less energy and could be a TV or radio wave.
All EM energy waves travel at the speed of light. No matter what their frequency or wavelength, they always move at the same speed. Some properties of waves, such as diffraction and interference, are also seen in EM radiation. Scientists have figured out that there are tiny particles in these waves; they are called photons. The photons are specific units, or packets, of energy. Sometimes those particles interact with each other and change the way the light originally behaved.
Listening to the HeavensAll types of EM radiation are useful to the world of science. Look at radio waves as an example. Radio stations and ham radio operators of Earth work with radio waves every day. Radio waves are used to carry communications from one point to another. Radio waves are also extremely important to astronomers. Astronomers are constantly listening to the radio waves of other galaxies to learn more about their stars. Stars give off large amounts of EM radiation across the entire spectrum, and we can study that radiation to learn more about the universe.
Radiation Doesn't Scare Us... MuchAn important idea you should always remember is that sometimes we use the word radiation. When you think of radiation, you probably think about nuclear power plants, bombs, and X-rays. Sure, those are all types of radiation. Nevertheless, more important to physics is the idea that all light is considered radiation. That means that everything from television and radio waves to gamma rays are all types of radiation. Think about the word LASER. The R stands for radiation, while a laser is just a souped-up flashlight. Think about heat. Most heat is actually infrared light being given off by an object. That heat is also radiation.
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Tour the EM Spectrum (ScienceAt NASA Video)
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