The Electromagnetic Spectrum

The "electromagnetic spectrum" is simply a phrase used to describe electromagnetic radiation of all wavelengths. This includes radio waves, microwaves, infrared, visible light, ultraviolet, x rays, gamma rays, and other electromagnetic radiation of longer and shorter wavelengths. Note that the names given to various portions of the spectrum are simply arbitrary labels imposed by humans; there is no definite wavelength where "radio waves" cease to be radio waves and suddenly become "microwaves". Rather, the various portions of the spectrum blend into one another and waves in between radio waves and microwaves interact with matter in a manner in between radio waves and microwaves. It is important to remember that there is no fundamental difference between any portion of the electromagnetic spectrum other than wavelength (and its dependent properties, frequency and energy). A radio wave is electromagnetic radiation of a long wavelength, and x rays are electromagnetic radiation of a shorter wavelength, but they are both electromagnetic radiation and their behavior is governed by the same laws.

If all electromagnetic radiation is fundamentally the same thing, you might ask, "Why don't we see radio waves like we see light?" or "Why do we need special infrared light bulbs to heat things up?" Although all portions of the electromagnetic spectrum are governed by the same laws, their different wavelengths and different energies allow them to have different effects on matter. Radio waves, for example, have such a long wave length and low energy that our eyes can't detect them and they pass through our bodies. It takes a metal antenna with special electronics to capture and amplify radio waves. Likewise, infrared radiation is of wavelengths that are easily absorbed by matter and turned into heat, and x rays are radiation of wavelengths that can pass through soft tissue but are stopped by bone. The wonderful variety of the electromagnetic spectrum is all a result of the same laws, applied to different wavelengths and energies.

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