use photocell in a sentence.
In his 1986 book, The Blind Watchmaker, Dawkins comments:Any engineer would naturally assume that the photocells would point towards the light, with their wires leading backwards towards the brain.
This means that the light, instead of being granted an unrestricted passage to the photocells, has to pass through a forest of connecting wires, presumably suffering at least some attenuation and distortion (actually, probably not much but, still, it is the principle of the thing that would offend any tidy-minded engineer).
The little metal wires that are silk screened on to solar panels collect these free electrons and transport them to the edge of a photocell, where they can be used to drive a load on their way back to the substrate from which they've been liberated.
This is a wonderful book because it covers so much ground and the writing and drawings give a physical sense of the topics: static electricity, magnetism, electrochemical cells, induction and capacitance, even semiconductors (cat's whisker detectors and selenium photocells).
I would also put a photocell on the device inside the internal shifter which would also set off the self-destruct mechanism.
I thought about this google challange thing, and I figured a tiny rover with motors from cell phone vibrators, an atmel chip wrapped in foil, a capacitor storage and tiny photocell, would be best.