While there isn't a single, definitive list of "7 types of light," the phrase most commonly refers to the different categories of the electromagnetic spectrum, which is a fundamental concept in physics. These are all forms of light, but most are invisible to the human eye. They are ordered by wavelength, from the longest to the shortest.
The 7 types of light in order are:
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Radio Waves: These have the longest wavelengths and are used for radio, television, and wireless communication.
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Microwaves: With shorter wavelengths than radio waves, these are used for heating food, radar, and satellite communication.
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Infrared (IR) Radiation: We often feel this as heat. It is used in thermal imaging, remote controls, and toasters.
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Visible Light: This is the only part of the spectrum that is visible to the human eye. It is what we perceive as all the colors of the rainbow.
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Ultraviolet (UV) Radiation: This has shorter wavelengths than visible light and is what causes sunburns. It is also used in sterilization and for blacklights.
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X-Rays: These high-energy waves are used in medical imaging to see inside the body and in airport security scanners.
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Gamma Rays: These are the most energetic waves with the shortest wavelengths. They are produced by nuclear reactions and are used in cancer treatment and for sterilizing medical equipment.