{"id":43,"date":"2022-01-18T16:34:14","date_gmt":"2022-01-18T21:34:14","guid":{"rendered":"https:\/\/pressbooks.bccampus.ca\/basiclightingforelectricianslevel2\/chapter\/terms-and-definitions\/"},"modified":"2022-09-14T15:56:59","modified_gmt":"2022-09-14T19:56:59","slug":"terms-and-definitions","status":"publish","type":"chapter","link":"https:\/\/pressbooks.bccampus.ca\/basiclightingforelectricianslevel2\/chapter\/terms-and-definitions\/","title":{"raw":"Brightness vs Illumination","rendered":"Brightness vs Illumination"},"content":{"raw":"\n<h2>Luminous Flux<\/h2>\nThis describes the total <strong>Quantity<\/strong> of light output from a source. The unit for luminous flux is the <strong>Lumen<\/strong> (Lm), and this represents how much visible light is emitted from the lamp in every direction.\n<h2>Candela<\/h2>\nThe term <strong>Candela<\/strong> (cd) is often associated with <strong>Luminous Flux<\/strong>, but specifically, <strong>Candela<\/strong> refers to the amount of light emitted in a particular direction. Both <strong>Candela<\/strong> and <strong>Lumens<\/strong> are used in lighting equations, and they have an equivalency of:\n<p style=\"text-align: center\">[latex]\\text{1 candela}=\\text{12.57 lumens} [\/latex]<\/p>\n&nbsp;\n\nThis means that a light source would have to emit 12.57 lumens in every direction in order to guarantee that 1 candela of illumination was measured in any particular direction.\n<h2>Luminous Flux Density<\/h2>\nThe density of light flux measured with a <strong>photometer <\/strong>on a surface is referred to as <strong>illumination<\/strong> or <strong>luminous flux density<\/strong>. The unit it is measured in is called the Lux (Lx) or foot-candle (fc) and represents how bright a surface is.\n\n<img class=\"aligncenter wp-image-44 size-full\" src=\"https:\/\/pressbooks.bccampus.ca\/basiclightingforelectricianslevel2\/wp-content\/uploads\/sites\/1597\/2022\/01\/Lumens-and-lux.png\" alt=\"\" width=\"640\" height=\"360\">\n","rendered":"<h2>Luminous Flux<\/h2>\n<p>This describes the total <strong>Quantity<\/strong> of light output from a source. The unit for luminous flux is the <strong>Lumen<\/strong> (Lm), and this represents how much visible light is emitted from the lamp in every direction.<\/p>\n<h2>Candela<\/h2>\n<p>The term <strong>Candela<\/strong> (cd) is often associated with <strong>Luminous Flux<\/strong>, but specifically, <strong>Candela<\/strong> refers to the amount of light emitted in a particular direction. Both <strong>Candela<\/strong> and <strong>Lumens<\/strong> are used in lighting equations, and they have an equivalency of:<\/p>\n<p style=\"text-align: center\">[latex]\\text{1 candela}=\\text{12.57 lumens}[\/latex]<\/p>\n<p>&nbsp;<\/p>\n<p>This means that a light source would have to emit 12.57 lumens in every direction in order to guarantee that 1 candela of illumination was measured in any particular direction.<\/p>\n<h2>Luminous Flux Density<\/h2>\n<p>The density of light flux measured with a <strong>photometer <\/strong>on a surface is referred to as <strong>illumination<\/strong> or <strong>luminous flux density<\/strong>. The unit it is measured in is called the Lux (Lx) or foot-candle (fc) and represents how bright a surface is.<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"aligncenter wp-image-44 size-full\" src=\"https:\/\/pressbooks.bccampus.ca\/basiclightingforelectricianslevel2\/wp-content\/uploads\/sites\/1597\/2022\/01\/Lumens-and-lux.png\" alt=\"\" width=\"640\" height=\"360\" \/><\/p>\n","protected":false},"author":848,"menu_order":1,"template":"","meta":{"pb_show_title":"on","pb_short_title":"","pb_subtitle":"","pb_authors":["alee59"],"pb_section_license":"all-rights-reserved"},"chapter-type":[],"contributor":[61],"license":[59],"class_list":["post-43","chapter","type-chapter","status-publish","hentry","contributor-alee59","license-all-rights-reserved"],"part":41,"_links":{"self":[{"href":"https:\/\/pressbooks.bccampus.ca\/basiclightingforelectricianslevel2\/wp-json\/pressbooks\/v2\/chapters\/43","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/pressbooks.bccampus.ca\/basiclightingforelectricianslevel2\/wp-json\/pressbooks\/v2\/chapters"}],"about":[{"href":"https:\/\/pressbooks.bccampus.ca\/basiclightingforelectricianslevel2\/wp-json\/wp\/v2\/types\/chapter"}],"author":[{"embeddable":true,"href":"https:\/\/pressbooks.bccampus.ca\/basiclightingforelectricianslevel2\/wp-json\/wp\/v2\/users\/848"}],"version-history":[{"count":1,"href":"https:\/\/pressbooks.bccampus.ca\/basiclightingforelectricianslevel2\/wp-json\/pressbooks\/v2\/chapters\/43\/revisions"}],"predecessor-version":[{"id":397,"href":"https:\/\/pressbooks.bccampus.ca\/basiclightingforelectricianslevel2\/wp-json\/pressbooks\/v2\/chapters\/43\/revisions\/397"}],"part":[{"href":"https:\/\/pressbooks.bccampus.ca\/basiclightingforelectricianslevel2\/wp-json\/pressbooks\/v2\/parts\/41"}],"metadata":[{"href":"https:\/\/pressbooks.bccampus.ca\/basiclightingforelectricianslevel2\/wp-json\/pressbooks\/v2\/chapters\/43\/metadata\/"}],"wp:attachment":[{"href":"https:\/\/pressbooks.bccampus.ca\/basiclightingforelectricianslevel2\/wp-json\/wp\/v2\/media?parent=43"}],"wp:term":[{"taxonomy":"chapter-type","embeddable":true,"href":"https:\/\/pressbooks.bccampus.ca\/basiclightingforelectricianslevel2\/wp-json\/pressbooks\/v2\/chapter-type?post=43"},{"taxonomy":"contributor","embeddable":true,"href":"https:\/\/pressbooks.bccampus.ca\/basiclightingforelectricianslevel2\/wp-json\/wp\/v2\/contributor?post=43"},{"taxonomy":"license","embeddable":true,"href":"https:\/\/pressbooks.bccampus.ca\/basiclightingforelectricianslevel2\/wp-json\/wp\/v2\/license?post=43"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}