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| − | [[Category: | + | [[Category: Physics]] |
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== Explanation == | == Explanation == | ||
| − | Light is a part of the [[electromagnetic spectrum]] that are visible to the human [[eye]]. Light is made up of the [[elementary particle]] known as [[photon]] travelling at different [[wavelength]]s determined by their [[energy]]. When photons travel at a wavelength range from 400 to 700 | + | [[File:Visible_Light.jpg|thumb|450|right|The visible spectrum of the electromagnetic spectrum.]] |
| + | Light is a part of the [[electromagnetic spectrum]] that are visible to the human [[eye]]. Light is made up of the [[elementary particle]] known as [[photon]] travelling at different [[wavelength]]s determined by their [[energy]]. When photons travel at a wavelength range from 400 to 700 nanometers, it radiates as visible light. Like any elementary particles, photons exhibit the [[wave-particle duality]]. The visible light can be split into its constituent wavelengths by passing the light through a [[prism]]. This is known as light [[dispersion]]. A [[rainbow]] is the most common example that practically displays this spectacular phenomenon. | ||
== Frequently Asked Questions == | == Frequently Asked Questions == | ||
=== Why only the visible part of the electromagnetic spectrum is sensed by the human eye? === | === Why only the visible part of the electromagnetic spectrum is sensed by the human eye? === | ||
| − | Our eyes are sensitive to only the 400 to 700 | + | Our eyes are sensitive to only the 400 to 700 nanometer part of the spectrum, because of the way we evolved on Earth. [[Electromagnetic radiation]] within this range is the only light that reached the ocean depths. As eyes evolved inside the waters during the historic periods, it is believed that this could be the reason why our [[photoreceptor]]s are evolved to be sensitive to this range. |
=== What is the source of light? === | === What is the source of light? === | ||
The primary sources of light in the universe are the [[star]]s that emit radiation, more in the visible spectrum, analogous to a [[black-body]]. In our solar system, the [[Sun]] is the source of light. On [[Earth]], there are other sources of light, like candles, bulbs, lamps and similar artificial sources. Visible light is also emitted when the [[electron]]s of [[atom]]s drop from a higher energy state to a lower energy state. This is the basic principle of [[light-emitting diode|LEDs]] and [[laser]]s. | The primary sources of light in the universe are the [[star]]s that emit radiation, more in the visible spectrum, analogous to a [[black-body]]. In our solar system, the [[Sun]] is the source of light. On [[Earth]], there are other sources of light, like candles, bulbs, lamps and similar artificial sources. Visible light is also emitted when the [[electron]]s of [[atom]]s drop from a higher energy state to a lower energy state. This is the basic principle of [[light-emitting diode|LEDs]] and [[laser]]s. | ||
| − | === Are there any other | + | === Are there any other colors that humans cannot see? === |
| − | Humans perceive | + | Humans perceive colors when different types of [[cone cell]]s in their eyes detect specific wavelengths that are found in the visible part of the electromagnetic spectrum. As light is something humans can see within this spectrum, there are no other colors. However, if the lens of the eye is removed, can perceive wavelengths shorter than 400 nm, which is [[ultraviolet]]. Claude Monet, a French painter who had undergone a cataracts surgery, perceived colors in ultraviolet as his lens was removed. |