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There are waves of energy and light moving all around us. There are TV and Radio 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 electric and magnetic characteristics. Scientists classify them by their frequency, going from HIGH to LOW FREQUENCY. When a wave has a lot of energy, 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. Scientists have figured out that there are tiny particles in the waves. Those particles are called PHOTONS. The photons are specific units, or packets, of energy. RADIATION, YOU AREN'T SO SCARY There is an important idea you should always remember when we talk about energy. 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. More important to Physics is the idea that all light is considered radiation. That fact means everything from radio waves to gamma rays are all types of radiation. Think about the word lasers, the "R" stands for radiation, but it's just a souped up flashlight. |