It is my understanding that you can only heat something up to the temerpature the source of heat is. so if i have 10 1 sqft lenses focussing on 1 1sqft lens i would get 10x the energy [roughly] the 1sqft lens would focus. but if i did this in several levels making a million 1sqft of mirrors focussing to a thousand, focussing to 1 I would not get a million times the energy [roughly]
Is this correct?
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-i want to justify a high atmosphere magnifier rendering the Land below into dust. id rather it was a passive effect than needs a solar array and emitters of some kind.
In: Physics
Unfortunately you can’t just stack lenses like that, or rather, it won’t give you the effect you are after.
A magnifying glass can make the Sun look bigger from the point of view of a small spot on the ground. This small spot thus gets more sunlight, and so gets hotter. A large magnifying glass in the sky could do the same for a big area of ground (though still much smaller than the magnifying glass itself). To heat an entire hemisphere would require a magnifying glass many times the diameter of the Earth, presumably floating around in orbit.
[Here](https://what-if.xkcd.com/145/) is a good xkcd explanation.
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