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  • Giant Fresnel Lens Deathray: An Experiment in Optics

    @SelenaH5 Please read this page again and again and again until you understand it.1. The lens focuses a large area of sunlight to a fine point. Whatever is at that point gets very hot, even just air, it starts to glow brightly and start to burn - even metals and glass will melt, concrete burns. This includes you, your hand, your brain if you're that uncautious. This is dangerous stuff.2. The glow can get as bright as the sun, after all it comes from the sun, and that will damage the eyes of anyone looking at it. You do not want to blind anyone, a school is fir the education of the ignorant, and it's likely someone who's ignorant will ignore or not understand any warnings you put up, Never underestimate the capacity of the human being to be stupid, Health and Safety is designed to plan f...see more »@SelenaH5 Please read this page again and again and again until you understand it.1. The lens focuses a large area of sunlight to a fine point. Whatever is at that point gets very hot, even just air, it starts to glow brightly and start to burn - even metals and glass will melt, concrete burns. This includes you, your hand, your brain if you're that uncautious. This is dangerous stuff.2. The glow can get as bright as the sun, after all it comes from the sun, and that will damage the eyes of anyone looking at it. You do not want to blind anyone, a school is fir the education of the ignorant, and it's likely someone who's ignorant will ignore or not understand any warnings you put up, Never underestimate the capacity of the human being to be stupid, Health and Safety is designed to plan for these as among the vulnerable.3. The project may cause other people to try to emulate it without knowing about the need for safety precautions.So, just as a school is unlikely to allow someone to work with thermite, which is well within the capacity of most children to put together, equally it should not allow anyone to do this with a lens larger than 30cm across. Working on this scale is withi one order of magnitude in danger, and that's far too dangerous to be allowed in a school project, sorry.

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