Why Does a Hole in Paper Show an Eclipse Shadow?

[adjacent]

On an eclipsed day,for example,a partially eclipsed day,when I make a hole in a piece of paper and place it on the sunlight,I find that the shadow(Or whatever)of the hole appears like the eclipse.Why?

 

[D H]

http://en.wikipedia.org/wiki/Pinhole_camera.

 

[adjacent]

Thank you but I don't understand why an image is formed.Is the hole bending the light,like lenses?

 

[D H]

Thank you but I don't understand why an image is formed.Is the hole bending the light,like lenses?

No. Look at the ray trace diagram:

The light coming from any given part of the tree follows a straight line from that part of the tree to the pinhole and then to the rear of the camera. The line from the trunk of the tree to the pinhole and the line from the top of the tree to the pinhole are different lines. They enter the pinhole at an angle with respect to one another, and thus they hit the rear of the camera at different spots.

Suppose the hole was bigger. Now light coming from the bottom of the tree won't hit a single spot on the rear of the camera. It will instead form a circle. The same applies to light from the top of the tree. Make the hole big enough and those circles will overlap. You won't see an image at all. This overlapping effect still occurs with a pinhole, but it's small because the pinhole is small. A pinhole camera is always going to appear to be a bit out of focus because of this. You can get a better focus by making the pinhole smaller and smaller, but this reduces the amount of light coming in. With a pinhole camera there's always a trade-off between fuzziness and intensity.

 

[Vanadium 50]

Which part of the article didn't you understand? There's a picture explaining it and everything.

 

[adjacent]

Ah.Now I Understand it.Thanks D H.