[{"data":1,"prerenderedAt":-1},["ShallowReactive",2],{"doc-detail-142742-en":3,"doc-seo-142742-105":30,"detail-sidebar-cat-0-en-105":90},{"code":4,"msg":5,"data":6},0,"success",{"doc_id":7,"user_id":8,"nickname":9,"user_avatar":10,"doc_module":4,"category_id":11,"category_name":12,"doc_title":13,"doc_description":14,"doc_content":15,"file_id":16,"file_url":17,"file_type":18,"file_size":19,"view_count":4,"is_deleted":4,"is_public":20,"is_downloadable":20,"audit_status":20,"page_count":21,"language":22,"language_code":23,"site_id":24,"html_lang":23,"table_of_contents":25,"faqs":26,"seo_title":27,"seo_description":14,"update_tm":28,"read_time":29},142742,2336475401981,"Chumphorn","https://ap-avatar.wpscdn.com/avatar/22000c94efd8d5204d?x-image-process=image/resize,m_fixed,w_180,h_180&k=1786935347598174694",6,"Technology","Light of a Different Color - Black Light and UV Fluorescence","Explains how black lights produce brilliant visible effects despite emitting invisible ultraviolet (UV) radiation. Covers UV categories (UVA, UVB, UVC), including relative risks and real-world uses such as tanning and sterilization. Then details fluorescence, describing how pigments absorb UV and re-emit visible light through excited electronic states, causing objects to appear to glow under black light and stop instantly when it is removed. Introduces related phenomena including phosphorescence and triboluminescence.","A  \npiece of white cloth is placed underneath a strange-looking purplish light. It glows brilliantly.  \nWhite powder placed underneath this same light emanates a brilliant radiance. A beaker of green fluid glows with a supernatural hue. Is this the stuff of science fiction? Hardly. The above phenomena are all a result of a special type of light known as a black light.  \nUV connection  \nThe black light gets its name because itemits a type of light that you cannot see. Actually, most types of light, or electromagnetic radiation, are invisible to the naked eye (see figure opposite page) . Our eyes can detect only a tiny sliver of the entire electromagnetic spectrum, appropriately referred to as the “visible” region. A black light gives off radiation in the form of ultraviolet (UV) light. Because most sources of UV light emit violet light along with the UV light, the luminosity given off by a black light source appears tobe violet. However, the actual UV light that is emitted is invisible to the naked eye.  \nFor convenience purposes, UV light is often divided into three categories: UVA, UVB, and UVC. A black light makes use of UVA radiation—the longest UV light wavelength and very close in frequency to visible violet light. Of the three types of UV light, UVA carries the least amount of energy per photon, small packets in which light carries its energy. UVA is thus considered the least harmful to humans. However, care should be taken never to look directly at a black light, because prolonged exposure can be harmful to the eyes.  \nOther types of UV light have shorter wavelengths and thus have higher frequencies. They carry more energy per photon and can cause greater harm to living things. UVB light is responsible for sunburns, which have been linked to skin cancer and eye damage. Tanning salons use primarily UVB radiation. UVC light is used to sterilize surfaces and medical instruments. Because these rays are so energetic, they can kill bacteria and viruses. Some schools sterilize safety goggles with special cabinets that use UVC radiation.  \nFluorescence  \nCertain objects, when placed under a black light, appear different than under an ordinary white light. They may appear to be brighter or emit a completely different color altogether. Specialized pigments within these substances have the amazing ability to absorb energy of one wavelength and then reemit it as energy of a different wavelength. This absorption of UV light and emission as visible light is known as fluorescence.  \nIn the simplest case where fluorescence occurs in atoms, a black light emits photons of energy that are absorbed by electrons of the atom. These electrons are initially in the ground state, which is the lowest possible energy level that the electrons can occupy. However, upon absorbing a photon of UV energy, these electrons jump up to a higher energy level. This higher energy level is known as the excited state. However, this excited state is extremely unstable and only temporary. The electrons quickly return to the ground state, but as they do, they “stop off” at intermediate energy levels. With each stop, they have a choice between dissipating their excess energy as heat or emitting a photon of light. Because the total energy they absorbed all at once is now being emitted in more than one step—or dissipated as heat—each emitted photon has only a fraction of the energy of the initial  \nBy Brian Rohrig  \nUV light that was emitted. These lower energy photons also have a lower frequency—in the visible region of the spectrum, not the UV region.  \nMost fluorescent objects actually contain fluorescent pigments that are complex molecular substances. Fluorescence in these molecules is a more complex process that involves both the vibration of the molecule and changes in the electronic configuration.  \nBecause of fluorescence, substances often appear to be a different color under a black light. The wavelengths of the emitted black light may not correspond to the s","cbCaikVPj0i3F09Z","https://ap.wps.com/l/cbCaikVPj0i3F09Z","pdf",1346948,1,3,"English","en",105,"# UV connection\n## UVA, UVB, and UVC\n# Fluorescence\n## Excited states and emitted visible light\n## Fluorescent pigments and glow behavior\n# Phosphorescence\n## Glowing in the dark\n# Triboluminescence\n## Glow from mechanical action","[{\"question\":\"Why does a black light glow appear violet even though UV is invisible?\",\"answer\":\"A black light emits ultraviolet radiation that the eye cannot see. Many UV sources also emit some violet light, making the overall emitted light appear violet, even though the UV itself remains invisible to the naked eye.\"},{\"question\":\"What causes fluorescence under a black light?\",\"answer\":\"Fluorescent pigments absorb UV photons and excite electrons to higher energy levels. As electrons return through intermediate states, they emit lower-energy photons in the visible range, creating a glow that stops once the black light is removed.\"},{\"question\":\"How is phosphorescence different from fluorescence?\",\"answer\":\"Phosphorescent substances continue glowing after the light source is removed because their excited electrons remain in a higher state for longer and decay gradually. Fluorescent materials do not—once the excitation stops, they cease fluorescing quickly.\"}]","Light of a Different Color - Black Light and UV Fluorescence | PDF",1787687310,8,{"code":4,"msg":31,"data":32},"ok",{"site_id":24,"language":23,"slug":33,"title":13,"keywords":34,"description":14,"schema_data":35,"social_meta":85,"head_meta":87,"extra_data":89,"updated_unix":28},"light-of-a-different-color-black-light-and-uv-fluorescence","",{"@graph":36,"@context":84},[37,53,67],{"@type":38,"itemListElement":39},"BreadcrumbList",[40,44,48,50],{"item":41,"name":42,"@type":43,"position":20},"https://docshare.wps.com","Home","ListItem",{"item":45,"name":46,"@type":43,"position":47},"https://docshare.wps.com/document/","Document",2,{"item":49,"name":12,"@type":43,"position":21},"https://docshare.wps.com/document/technology/",{"item":51,"name":13,"@type":43,"position":52},"https://docshare.wps.com/document/light-of-a-different-color-black-light-and-uv-fluorescence/142742/",4,{"url":51,"name":13,"@type":54,"author":55,"headline":13,"publisher":57,"fileFormat":60,"inLanguage":23,"description":14,"dateModified":61,"datePublished":61,"encodingFormat":60,"isAccessibleForFree":62,"interactionStatistic":63},"DigitalDocument",{"name":9,"@type":56},"Person",{"url":41,"name":58,"@type":59},"DocShare","Organization","application/pdf","2026-08-25",true,{"@type":64,"interactionType":65,"userInteractionCount":4},"InteractionCounter",{"@type":66},"ViewAction",{"@type":68,"mainEntity":69},"FAQPage",[70,76,80],{"name":71,"@type":72,"acceptedAnswer":73},"Why does a black light glow appear violet even though UV is invisible?","Question",{"text":74,"@type":75},"A black light emits ultraviolet radiation that the eye cannot see. Many UV sources also emit some violet light, making the overall emitted light appear violet, even though the UV itself remains invisible to the naked eye.","Answer",{"name":77,"@type":72,"acceptedAnswer":78},"What causes fluorescence under a black light?",{"text":79,"@type":75},"Fluorescent pigments absorb UV photons and excite electrons to higher energy levels. As electrons return through intermediate states, they emit lower-energy photons in the visible range, creating a glow that stops once the black light is removed.",{"name":81,"@type":72,"acceptedAnswer":82},"How is phosphorescence different from fluorescence?",{"text":83,"@type":75},"Phosphorescent substances continue glowing after the light source is removed because their excited electrons remain in a higher state for longer and decay gradually. Fluorescent materials do not—once the excitation stops, they cease fluorescing quickly.","https://schema.org",{"og:url":51,"og:type":86,"og:title":13,"og:site_name":58,"og:description":14},"article",{"robots":88,"canonical":51},"index,follow",{"doc_id":7,"site_id":24},{"code":4,"msg":5,"data":91},[92,96,100,104,109,112,117,121,126,129,133],{"id":20,"doc_module":4,"doc_module_name":46,"category_name":93,"show_sort_weight":94,"slug":95},"Story & Novel",90,"story-novel",{"id":47,"doc_module":4,"doc_module_name":46,"category_name":97,"show_sort_weight":98,"slug":99},"Literature",80,"literature",{"id":52,"doc_module":4,"doc_module_name":46,"category_name":101,"show_sort_weight":102,"slug":103},"Exam",70,"exam",{"id":105,"doc_module":4,"doc_module_name":46,"category_name":106,"show_sort_weight":107,"slug":108},5,"Comic",60,"comic",{"id":11,"doc_module":4,"doc_module_name":46,"category_name":12,"show_sort_weight":110,"slug":111},50,"technology",{"id":113,"doc_module":4,"doc_module_name":46,"category_name":114,"show_sort_weight":115,"slug":116},7,"Healthcare",40,"healthcare",{"id":29,"doc_module":4,"doc_module_name":46,"category_name":118,"show_sort_weight":119,"slug":120},"Research & Report",30,"research-report",{"id":122,"doc_module":4,"doc_module_name":46,"category_name":123,"show_sort_weight":124,"slug":125},9,"Religion & Spirituality",20,"religion-spirituality",{"id":124,"doc_module":4,"doc_module_name":46,"category_name":127,"show_sort_weight":124,"slug":128},"World Cup","world-cup",{"id":130,"doc_module":4,"doc_module_name":46,"category_name":131,"show_sort_weight":130,"slug":132},10,"Lifestyle","lifestyle",{"id":134,"doc_module":4,"doc_module_name":46,"category_name":135,"show_sort_weight":105,"slug":136},19,"General","general"]