Questions tagged [luminous-flux]

Anything related to the *luminous flux* emitted by a light source. The luminous flux is a physical quantity used in photometry to measure the amount of light power radiated from a light source that can be perceived by the human eye. Its unit of measurement in the SI is the *lumen* (lm).

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Adding luminous intensities (cd)

How do I calculate the Luminous Intensity (cd) of multiple LEDs spread across a 1.5m2 internally illuminated sign element? I have done this by treating it as a point source and adding each led ...
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Convert lumen/m2 to candela/m2

I'm considering a monochromatic Blue LED (is an approximation) with the specs: Luminous flux=6lm, Dominant Wavelength=460nm Surface area= 1,5cm2 How can I calculate the solid angle value? There is ...
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Would I get a better lumen output and improved thermal characteristics for the same wattage if I get a higher rated LED? [closed]

I'm planning on building a bright DIY high CRI LED video/photo floodlight out of the following components and considerations: High-power Neutral White (4000K?) LED rated at 95 CRI No add-on lens so I ...
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323 views

Designing brake light with specific luminous intensity

I am currently designing a brake light for a Formula Student car and I am looking into existing solutions on the market for inspiration. The two specific solutions are this, and this. The LED I found ...
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What is the theoretical limit of lumen/watt for lighting systems?

Nowadays we see LEDs with 300 lumen per watt luminous efficacy. They still waste a lot of power as heat. Now what is the limit of electricity to light conversion? Say we build an LED with 100% ...
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360 views

How can I decrease the brightness of these BA-15 LED bulbs

I'm looking at these LED replacement bulbs for the interior of my sweet conversion van. I'm looking for a more efficient alternative to the BA15 bulbs that are in there already. These bulbs appear to ...
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815 views

High power LED vs. standard LED

How do high power LEDs with forward current of 350mA compare to bright 5mm LEDs with forward current of 20mA? If forward voltage is the same (same color) does that mean light output of 17.5 of 5mm ...
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Human perceived (relative) brightness of indicator LEDs

Humans looking at colored lights each at the same luminescence perceive yellow as the "brightest" color. Green is somewhat dimmer, and red is very much dimmer. Using a common formula for calculating ...
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Difference between incandescent/fluorescent/LED wattages?

If the numbers on the 'light output' table at the bottom of this page (here) is correct, and if I have a lamp (like this) that has a maximum wattage of 60 and takes incandescent bulbs: Does that mean ...
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1answer
74 views

Solid-state lighting [closed]

Background Consider the following technologies: 100 lm/W OLED (2008, source) 303 lm/W LED (2014, source) 94 lm/W LEP (2015, source) For growing food, the preferred measurement is Photosynthetically ...
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94 views

Why so different lumen efficiencies between mains and 22V halogen?

I was looking for data about halogen reflectors I just bought. They are 50W, 230V. On the package I read 320 lumen and that looked ridiculous to me, then I found this document by GE: Halogen Lamps ...
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180 views

Amount of light by an LED

I am supposed to use an light having the following specs. as described in the below statement. "A red light, equivalent in its luminescence to a 21 W light bulb is to be used." On an average how ...
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211 views

Does air flowing over a bulb affect the amount of lumens produced? [closed]

If a bulb is cooled by air flowing over it, would that change the way light is emitted? I see contradicting evidence that air cooling bulbs changes how much light is emitted because the cooler air ...