Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Solar Eclipse day

  1. Jul 10, 2013 #1

    adjacent

    User Avatar
    Gold Member

    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?
     
  2. jcsd
  3. Jul 10, 2013 #2

    D H

    User Avatar
    Staff Emeritus
    Science Advisor

  4. Jul 10, 2013 #3

    adjacent

    User Avatar
    Gold Member

    Thank you but I don't understand why an image is formed.Is the hole bending the light,like lenses?
     
  5. Jul 10, 2013 #4

    D H

    User Avatar
    Staff Emeritus
    Science Advisor

    No. Look at the ray trace diagram:

    400px-Pinhole-camera.svg.png

    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.
     
  6. Jul 10, 2013 #5

    Vanadium 50

    User Avatar
    Staff Emeritus
    Science Advisor
    Education Advisor

    Which part of the article didn't you understand? There's a picture explaining it and everything.
     
  7. Jul 10, 2013 #6

    adjacent

    User Avatar
    Gold Member

    Ah.Now I Understand it.Thanks D H.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: Solar Eclipse day
  1. Solar Eclipse (Replies: 1)

  2. Solar Eclipses (Replies: 2)

Loading...