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Basic doubt about a concept in Optics

  1. Jun 13, 2013 #1
    This may sound really silly but yeah, a plane mirror, and a white sheet of paper, both reflect all the wavelengths of light incident on them. So Instead of a plane mirror, if I use a white sheet of paper, Why don't I see a reflection of myself?
    I have studied ray diagrams, and i know how an image is formed by a plane mirror (which can be explained by ray diagrams). If a white sheet of paper can reflect all light, why can't I draw the same ray diagram with a white paper instead of a mirror?
  2. jcsd
  3. Jun 14, 2013 #2
    Maybe, because of the irregularities present on the surface of the paper, the reflected rays are not parallel..... so we don't obtain any sharp image as such.... the rays get dispersed.
  4. Jun 14, 2013 #3
    But what about smooth, laminated papers?
  5. Jun 14, 2013 #4


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    This is because of diffuse reflection; see these links:

    Specular vs. Diffuse Reflection
    Diffuse reflection (wiki)

    and you will see that it's not only the smoothness of the surface that plays a role - it's also the material itself. I'm pretty sure the material thickness also has some role.
    Last edited: Jun 14, 2013
  6. Jun 14, 2013 #5
    Thank you :-) And when we say that a white object appears white because it reflects all the wavelengths incident on it, does it mean that the intensity of the reflected light is proportional to the incident light or it need not meet this condition??? (for white light)
  7. Jun 14, 2013 #6

    Claude Bile

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    The term "white" typically means that all parts of the spectrum are reflected equally.

  8. Jun 14, 2013 #7


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    And some of the light may get absorbed by the white surface. As Claude said, White means that all parts of the spectrum are reflected equally. That means the intensity need not be same as the incident light intensity.
  9. Jun 14, 2013 #8
    I think the lamination is what is smooth - and it's clear (non-reflective). The paper below is still bumpy and had diffuse reflections.
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