Question by Joel: how can i use mirrors and lenses to magnify the sun on a wall?
I am trying to aid physics teachers develop an activity that magnifies and projects an image of the sun so they can see sunspots employing only mirrors and lenses.
Answer by JullyWum
The link beneath describes a straight-forward method ..
Making use of window blinds (darkened room) would enhance the contrast of the Sun’s image .. naturally a suitable sized hole in the blind is essential to permit sunlight to enter !
Using person converging (convex) lenses ..
Preferably mount the lens with the shorter focal length to obtain sunlight .. find the focus point utilizing a piece of white paper to locate the smallest sun-spot behind the lens (the paper may possibly get burnt /catch alight)
Arrange the 2nd (extended focal length) convex lens so that the sun-spot image of the first lens is a few cms additional from this lens than it’s focal length .. so the 2nd lens can type an inverted and magnified true image of the sun-spot on a screen really a distance behind the 2nd lens.
Trail and error will be necessary in putting the 2nd lens to get a final focused image (but don’t let the sun-spot get closer than the focal length of the 2nd lens .. that would make a virtual image which can’t kind on a screen)
In no way appear directly at the Sun through these lenses .. see the warning in the link.
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