It is much easier to say or write "two kilometers" than "two thousand meters." Generally, scientists use whatever units are easiest for the type of EM radiation they work with.Īstronomers who study radio waves tend to use wavelengths or frequencies. The short answer is that scientists don't like to use numbers any bigger or smaller than they have to. But why have three ways of describing things, each with a different set of physical units?Ĭomparison of wavelength, frequency and energy for the electromagnetic spectrum. Each of these three quantities for describing EM radiation are related to each other in a precise mathematical way. Frequency is measured in cycles per second, or Hertz. Radio waves have photons with low energies, microwave photons have a little more energy than radio waves, infrared photons have still more, then visible, ultraviolet, X-rays, and, the most energetic of all, gamma-rays.Įlectromagnetic radiation can be expressed in terms of energy, wavelength, or frequency. The different types of radiation are defined by the the amount of energy found in the photons. Each photon contains a certain amount of energy. Radio waves, gamma-rays, visible light, and all the other parts of the electromagnetic spectrum are electromagnetic radiation.Įlectromagnetic radiation can be described in terms of a stream of mass-less particles, called photons, each traveling in a wave-like pattern at the speed of light. The biggest gamma-ray generator of all is the Universe.Īre radio waves completely different physical objects than gamma-rays? They are produced in different processes and are detected in different ways, but they are not fundamentally different. Gamma ray: Doctors use gamma-ray imaging to see inside your body. Hot gases in the Universe also emit X-rays. ![]() X-ray: A dentist uses X-rays to image your teeth, and airport security uses them to see through your bag. "Hot" objects in space emit UV radiation as well. Ultraviolet: Ultraviolet radiation is emitted by the Sun and are the reason skin tans and burns. Fireflies, light bulbs, and stars all emit visible light. In space, infrared light helps us map the dust between stars. Infrared: Night vision goggles pick up the infrared light emitted by our skin and objects with heat. ![]() Microwave: Microwave radiation will cook your popcorn in just a few minutes, but is also used by astronomers to learn about the structure of nearby galaxies. Radio waves are also emitted by stars and gases in space. Click here for a great website giving information and examples of the different regions of the electromagnetic spectrum including radio waves, microwaves, infrared, visible light, ultraviolet, x-rays, and gamma rays.Radio: Your radio captures radio waves emitted by radio stations, bringing your favorite tunes. An example of this kind of radiation is infrared heaters because they give out infrared radiation to heat a room. Next to the low-energy part of the visible region (700nm) is infrared radiation (IR). A common example of UV radiation is sunlight. Next to the high-energy part of the visible region (400nm) is ultraviolet (UV) radiation. When all the waves are seen together, white light is seen. ![]() As you can see in the picture above, a wavelength of 400 nm represents violet and a wavelength of 700 nm represents red. The measure of wavelength determines the color on the visible spectrum. ![]() The visible region of the spectrum has wavelengths from about 400-700 nm. The region on this spectrum with the highest energy (so the shortest wavelengths) are gamma rays and the region with the lowest energy (so the longest wavelengths) are radio waves.
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