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Infrared and ultraviolet are part of the electromagnetic spectrum, along with visible light. Whereas visible light has a wavelength between 380–760 nanometers (nm), infrared radiation has a wavelength of 700 nm to 1 millimeter (mm), longer than that of visible light. Ultraviolet radiation has a wavelength shorter than visible light and is usually between 10–400 nm.
Neither infrared or ultraviolet are visible to the human eye. Both have their uses. Ultraviolet is an essential source of vitamin D, for example, while infrared can be used to determine the temperature of objects like clouds.
Read on for more information on these types of electromagnetic radiation and to learn of some of their similarities and uses.
Virtually every object emits infrared radiation, except for objects that have no temperature at all or measure at absolute zero temperature. Objects of different temperatures give off different amounts of infrared, and while it is invisible to the human eye, we can use sensors and equipment to detect infrared levels.
Infrared has a wavelength of 700 nm to 1 mm and starts at the end of the red edge of visible light, hence its name. The frequency, or the number of waves that occur in a second, of infrared is between 430 Terahertz (THz) and 300 Gigahertz (GHz). Infrared travels in straight lines and cannot bend around corners.
Every object that is above a temperature of absolute zero emits some infrared radiation, and the hotter the object, the more infrared it emits. Even objects like ice emit infrared. The sun is the single biggest source of infrared on our planet.
Infrared has a host of uses, but because it is invisible to the human eye, we need to use sensors and displays to identify it. The best known of these is infrared vision or infrared goggles. These detect the infrared radiation given off by objects and display the resulting image with hotter objects appearing in brighter colors than cooler objects. Infrared is also used as a heat source. Infrared cookers and heaters benefit from this type of radiation.
Ultraviolet (UV) sits at the other end of the natural light spectrum and is primarily emitted by the Sun, although artificial sources include tanning beds and some lights. It is essential for human survival but can be dangerous if you are overexposed to this type of radiation. Although invisible to the human eye, certain animals, such as bees, can see UV light.
Ultraviolet has a wavelength between 10–400 nm. It comes before the violent end of the visible light spectrum, which is why it’s named ultraviolet. Like infrared, UV is only capable of traveling in a straight line but, unlike infrared, not every object emits UV.
Very hot objects, such as the Sun, emit ultraviolet, and this is our primary natural source of UV. However, almost all forms of synthetic light produce some degree of UV. In some cases, this is the purpose of the light. Tanning beds, for example, use a UV emitting light to bathe the skin in this form of radiation. Halogen, mercury, and fluorescent lights all emit UV radiation.
Ultraviolet is an essential source of vitamin D for humans and other animals. It can also be used in agriculture to help plants grow and photosynthesize. It is used in cleaning, especially for killing bacteria, which is why some water filters include UV lights. UV lamps may also be used to help with joint and muscle complaints.
Infrared and ultraviolet are types of electromagnetic radiation, along with visible light. There are generally considered to be seven types of electromagnetic radiation:
Although they are both part of the electromagnetic spectrum, infrared and ultraviolet are quite different. The different properties of their waves mean that they have different practical applications:
Infrared and Ultraviolet are both forms of electromagnetic radiation and form part of the electromagnetic spectrum along with visible light, X-ray, and microwaves, as well as others. While infrared has a longer wavelength than natural light, ultraviolet has a shorter wavelength. Neither are visible to the human eye, and both have practical functions including communication and astronomy.
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Robert’s obsession with all things optical started early in life, when his optician father would bring home prototypes for Robert to play with. Nowadays, Robert is dedicated to helping others find the right optics for their needs. His hobbies include astronomy, astrophysics, and model building. Originally from Newark, NJ, he resides in Santa Fe, New Mexico, where the nighttime skies are filled with glittering stars.
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