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

Do we need a screen to view a real image?

  1. Oct 22, 2012 #1
    So, the question I ask is simple : " Is a screen necessary to view a real image?"

    For example, when I view my image at the 'concave mirror' side of a spoon, a real image is visible. Now, according to my book the image location should be between Centre and Focus. So, is the image actually kinda floating in air before spoon. If that is the case, why can't I see this air-suspended image from somewhere else.
    Can the images float like this in air? Or is it the air particles that become the screen in this case? Will this floating image be visible in a vacuum also?

    Please explain as well.
    Thanks a lot in advance.
     
  2. jcsd
  3. Oct 22, 2012 #2

    jtbell

    User Avatar

    Staff: Mentor

    You have to look at it from the right direction. Place your eye along the axis of the lens, on the image side, further away from the lens than the image location (maybe about 30 cm further away), and look towards the lens.

    At first glance, the image looks like it's "inside" the lens, but if you move your head around so as to look at the image from slightly different directions, you should be able to convince yourself that the image is actually between the lens and your eye.

    Hold a pencil or pen point between the lens and your eye, and move it back and forth. You should be able to put it in a location where the image appears to be "stuck" to it as you move your head from side to side.
     
  4. Oct 22, 2012 #3

    Doc Al

    User Avatar

    Staff: Mentor

    Yes.
    No.
    Yes.
     
  5. Oct 22, 2012 #4

    sophiecentaur

    User Avatar
    Science Advisor
    Gold Member

    You don't need a screen to see a real image but (putting things the other way round) to see an image on a screen (project it), it has to be real. All this means is that the rays (in a ray construction) actually emanate from real locations in space. So the rays have to converge at that point - so they can then leave the point and reach your eye.
    Plenty of optical instruments have real images formed inside them - like telescopes and microscopes - you then observe this real image with an eyepiece which then forms a virtual image at a convenient distance for viewing.
     
  6. Oct 22, 2012 #5
    What you are talking about is an optical illusion. The image only seems to float in mid air. There is nothing at that location. The real image location is on your retina. That's why it is also called a virtual image.
     
  7. Oct 22, 2012 #6

    Doc Al

    User Avatar

    Staff: Mentor

    You have it backwards. In this case the image is actually "floating" in mid air--it's no illusion. That's why it's called a real image--the light is really there.
     
  8. Oct 22, 2012 #7

    sophiecentaur

    User Avatar
    Science Advisor
    Gold Member

    Everything you see is because of a real image formed on your retina. Your eye lens forms that, whether the (outside) image you are looking at is real or virtual.
     
  9. Oct 22, 2012 #8
  10. Oct 22, 2012 #9

    sophiecentaur

    User Avatar
    Science Advisor
    Gold Member

Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: Do we need a screen to view a real image?
Loading...