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As plane mirrors always form virtual images and virtual images can not be obtained on a screen then how can we obtain the image of sun on wall or anything (screen) by plane mirror as on sunny day. Usually children here in India do mischief while focussing that light on other people's eyes.

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  • $\begingroup$ That might be explained in terms of virtual objects. When a convergent beam of light is blocked by placing a mirror in between, it creates something called a virtual object which can create real images. $\endgroup$ Commented Apr 10, 2017 at 15:45

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Reflecting sunlight with a mirror doesn't create an image. It creates a area which appears brighter than the surrounding area. This is because more photons are striking that area than the surrounding area. The same happens if you reflect the light into someone's eyes.

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  • $\begingroup$ Isn't that what a real image is? $\endgroup$
    – Silica19
    Commented Dec 23, 2022 at 8:19
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A small mirror that reflects the sunlight creates a patch on the wall that is the same size as the mirror, but convolved with the (angular) size of the sun.

This is, in some sense, like a "pinhole camera" - except that the light is being reflected rather than transmitted by the "pinhole" (the small mirror).

If the mirror is small, and the distance to the screen/wall is large, you will in fact create an image of the sun - you can confirm this by seeing that if a cloud moves in front of the sun, you will see the image of the cloud.

I tried to illustrate that below. On the left is the situation of a "small mirror" generating an image of the sun; on the right, a "small sun, large mirror" situation where the image is essentially the image of the mirror. Of course any real situation is somewhere between these two.

enter image description here

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