luminous flux Lumen is the unit in which luminous flux, the amount of light a light bulb or luminaire emits, is measured. So put simply: How much light comes out of the light bulb or luminaire?
light intensity Light intensity on the other hand is measured in lux and indicates the luminous flux emitted by a light source to illuminate a specific area. So: How much light reaches the area lit up? Example: 1 lux = if the luminous flux of 1 lumen lights up an area of 1 square meter evenly.
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