{"id":45,"date":"2021-01-24T19:45:24","date_gmt":"2021-01-25T00:45:24","guid":{"rendered":"https:\/\/pressbooks.bccampus.ca\/lightingforelectricians\/chapter\/terms-and-definitions\/"},"modified":"2021-04-21T14:41:05","modified_gmt":"2021-04-21T18:41:05","slug":"terms-and-definitions","status":"publish","type":"chapter","link":"https:\/\/pressbooks.bccampus.ca\/lightingforelectricians\/chapter\/terms-and-definitions\/","title":{"raw":"Brightness vs Illumination","rendered":"Brightness vs Illumination"},"content":{"raw":"

Luminous Flux<\/h2>\r\nThis describes the total Quantity<\/strong> of light output from a source. The unit for luminous flux is the Lumen<\/strong> (Lm), and this represents how much visible light is emitted from the lamp in every direction.\r\n

Candela<\/h2>\r\nThe term Candela<\/strong> (cd) is often associated with Luminous Flux<\/strong>, but specifically, Candela<\/strong> refers to the amount of light emitted in a particular direction. Both Candela<\/strong> and Lumens<\/strong> are used in lighting equations, and they have an equivalency of:\r\n

[latex]\\text{1 candela}=\\text{12.57 lumens} [\/latex]<\/p>\r\n \r\n\r\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.\r\n

Luminous Flux Density<\/h2>\r\nThe density of light flux measured with a photometer <\/strong>on a surface is referred to as illumination<\/strong> or 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.\r\n\r\n\"\"","rendered":"

Luminous Flux<\/h2>\n

This describes the total Quantity<\/strong> of light output from a source. The unit for luminous flux is the Lumen<\/strong> (Lm), and this represents how much visible light is emitted from the lamp in every direction.<\/p>\n

Candela<\/h2>\n

The term Candela<\/strong> (cd) is often associated with Luminous Flux<\/strong>, but specifically, Candela<\/strong> refers to the amount of light emitted in a particular direction. Both Candela<\/strong> and Lumens<\/strong> are used in lighting equations, and they have an equivalency of:<\/p>\n

\"\text{1 candela}=\text{12.57 lumens} \"<\/p>\n

 <\/p>\n

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

Luminous Flux Density<\/h2>\n

The density of light flux measured with a photometer <\/strong>on a surface is referred to as illumination<\/strong> or 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

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