Do 2 bulbs with 500 lumens provide the same illumination as one with 1000 lumens?
Do 2 bulbs with 500 lumens provide the same illumination as one with 1000 lumens?


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.

You need to understand (at least in a basic way) the difference between


Illuminance (Lux)
Luminous Intensity (Candela)
Luminous Flux (Lumens)


Lumens are a measure of luminous flux not of illuminance (which is closest to what you probably mean by illumination).



Two 500-lumen bulbs might produce very different values of Illuminance as one 1000-lumen bulb.

Two 500-lumen bulbs produce the same luminous flux as one 1000-lumen bulb.



If you were specifying some office space and needed to meet some regulations, you'd need to understand these distinctions. 

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.

You can buy light-meters that measure illuminance. I suppose an old-school photographer's light-meter makes a reasonable substitute.

The marketing departments of different manufacturers/distributors lie in different ways and different light-fittings are likely to make a difference to illuminance.