So if the degree of reflectance is a constant, then it will be added to each separate light source. Reflectance is the measure of light reflected by a surface.Įvery surface absorbs some of the light that is projected on it, this is measured as Reflectance. The simple answer seems to be that the intensity of the lamp would be the same, but the absorption by the reflecting surface (in this case a projection screen). The question given to me is specific to projecting images in large spaces, indoor or outdoors, and whether two lamps of 4500 lumens projecting on the same screen would be equivalent to a single 9000 lumens lamp. This because it is the combination of Lumens and Reflectance that gives us the perceived brightness. This thread caused my thinking to change so I have different conclusion. I was asked this question by someone who works with large projection screens and I found this thread researching the answer. The marketing departments of different manufacturers/distributors lie in different ways and different light-fittings are likely to make a difference to illuminance. I suppose an old-school photographer's light-meter makes a reasonable substitute. You can buy light-meters that measure illuminance. If you are a home-owner choosing between light fittings or bulbs made 8,000 miles away, it is likely that this sort of distinction is unimportant to you. If you were specifying some office space and needed to meet some regulations, you'd need to understand these distinctions. Two 500-lumen bulbs produce the same luminous flux as one 1000-lumen bulb. Two 500-lumen bulbs might produce very different values of Illuminance as one 1000-lumen bulb. Lumens are a measure of luminous flux not of illuminance (which is closest to what you probably mean by illumination). You need to understand (at least in a basic way) the difference between I agree with our local Retired Master Electrician's answer but if you want to put on your physicist's hat, the answer is no. Due to the wider light distribution, the light source no longer appears as bright.Do 2 bulbs with 500 lumens provide the same illumination as one with 1000 lumens? Depending on the installation situation, such a foil can be attached in front of the LED illuminant. What this means is that power (represented by P) is equal to the current (Represented by I) in amps flowing through the circuit, which is squared and multiplied by the resistor value (Represented in R) in ohms.įurthermore, there are so-called diffuser foils, which cause a scattering of the light. When using resistors, you’ll need to know the power required for your project so you’ll calculate this using a LED resistor value formula like this one: In many states, there are regulations to the brightness (and colors) of LEDs on cars, which is why this is important to take note of. LED dimmers are available for installation in place of the light switch and also as intermediate plugs.ĭimming an LED light is as easy as adding resistors to the connection or even several resistors, to ensure you get the right brightness – this is called analog dimming. This way you can always adjust the brightness accordingly. To darken the lamp if necessary, the use of a dimmer is recommended. Many light sources are only too bright in certain situations. Here you can find out what you can do against LED lights that are too bright and dazzling. Can LED lights be dimmed? Well, of course they can! In fact there’s more than one way to achieve this. Ordinary light bulbs can be dimmed by changing their input voltage, the same cannot be said for LED lights.
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