I didn't find an answer for this.
A friend and me argued about the brightness-impact of multiple bulbs/torches.
I told him, that 2 torches with the same power (the same amount of lumen and everything) hold side by side, won't be a difference in lumen, if you place the measure-device directly in the center of the "beam". So: The brightness is the same.
Means: If I point to the lumen-measure device with one torch (maybe ~0.5m distance), adding another would have no impact on the result, if it has exactly the same power.
He denied and said, that the more torches/bulbs you add, the more brightness you will get.
He said, that if you add another torch, you see 2 rings of light: The center beam contains the power of both, but at the outside (edges), the beams divide and there would be lesser power, where because there is just the beam of one torch.
I draw a picture to show the Idea:
I said, that you don't have more brightness, but you have a better illumination, which let you think that the light is stronger. But if somebody "beams" to your eyes with one torch, adding another with the same attributes won't make a difference in brightness, if you hold them close together.
If you would put 1000 torches next to each other, it won't be much brighter, but the illumination is of course bigger and this may let you think, that there is stronger light.
Who of us was right? I couldn't get an evidence for my theory, because I lack the required items.
I hope you understand what I mean, my english isn't the best. 🙂
I hope there are some of you, who can give me a good answer to this. We "fight" about this point since months. 😀 I couldn't find an evidence on the internet.
Image courtesy of Rod Nave's
Best Answer
He's right.
If you shine two flashlights on an object, there is twice as much light hitting it as if you used one flashlight.
It's as simple as that.