Thanks again..He still claims law of diminishing returns, "in a closed-loop system." It is easier to blow out a light bulb with him I suppose. The only law of diminishing returns I know that it relates to would be economics specifically when an application yields ineffectiveness.
I was discussing solar cells with my friend and we began talking about law of diminishing returns when once a light is lit up, it will send some of the light to the solar cell and energy back into the bulb. When it goes back to the bulb, it won't have as much energy as it did to light the bulb...