Why do you get a lot more light from a diffuser lamp than you would just with a bulb? Why do you get a lot more light from a diffuser lamp than you would just with a bulb? Isn't that an oddity of physics? I mean here you are, a little lightbulb in your hand -- not much happening; then you put a diffuser or reflector behind it, and you get this huge burst of light. Doesn't that mean that the light has multiplied without extra energy input? That's impossible though. What's happening there? Answer by Steve You don't get more light; you get light coming from a lot more directions than the essentially point source of the bulb. You can verify this with a photographer's light meter. Answer by Heinz H Not an expert, but let me try: You and @steve are correct, the amount of lumens (a measure for the visible light-"current") coming out of the lamp does NOT change. The small filament area of the bulb has an even light light distribution in all directions. Assuming the room is predominantly 'black', with few reflections coming back to you, you see only what enters into your pupil, coming DIRECTLY from the (almost) point source. I am too lazy to do the calculation, but you are NOT seeing maybe &gt; 99.99+ % of the lumens emanating from the point source. The magic words in your question are "reflector", and "behind" the point source: If you use a reflector e.g.