Really elementary question- Do Magnifying Glasses produce more photons than what is put into them? If they don't, how do they make light appear brighter-
Such as this scenerio:
Small light through narrow end of magnifying glass producing a brighter light on the other end.
No, they only focus the photons into a smaller area. The light appears brighter because the intensity has increased, since you now have the same power (energy per unit of time) over a smaller area: $$I=P/A $$
No, it does not. Magnifying glasses cannot create photons. It only concentrates photons in a small region, resulting into a bright spot. If there are more photons in some region and the total number of photons is conserved, then there is a neighboring region with missing photons. This region is therefore darker than regions off the magnifying glass.
This is the rundown: a convex lens collects light over a large area and bends it all toward its center, so it creates a focused concentration of what its given. This can be likened somewhat to a river, which can be made of little streams all directed to one spot. You may look at the little streams and the river, and say the river is greater, but the river can never really total more than the water its given. A lens producing photons would violate the law of the conservation of matter ;)
