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If i can see him, can he see me?

  1. Jul 9, 2011 #1
    Imagine you are in a dark field. A man with a flashlight is looking for you. you sse the light from his flashlight.

    doesn't this mean he should be able to see you? after all, photons are reflecting off of you if his light reaches your eyes.

    Or is it simply that his eyes have adjusted to the brightneas of the objects he is directly shining his light on?

    sorry for any typos, on my phone and the text doesn't show, om typing blindly here.
  2. jcsd
  3. Jul 10, 2011 #2
    I think there is no reason he shouldn't be able to see you.
    Yes , you won't be able to see him as the photons reflecting from his body aren't sufficient enough to make an image in ur eye.
  4. Jul 10, 2011 #3
    He might see you, but may not recognize you because you are not giving off as much light. To say that you see his flashlight or light from his flashlight does not mean that you see all of the light from his flashlight. To say that he sees you does not mean that he sees all of the light reflecting from you. Yes he should see some of the light reflecting from you, but it may not be enough to distinguish you from the rest of the environment.
  5. Jul 10, 2011 #4
    That depends on the intensity of flashlight and distance from the source.
  6. Jul 10, 2011 #5


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    There's a bit of mixing concepts here. It is true that, unless you are a perfect black body absorber, which you are not, you WILL reflect many of the photons that strike you. However the human eye is not able to detect light of sufficiently low amount. If you are 10 feet from the man then there is a good chance that he will be able to see you as long as he has a decent flashlight. But if I'm about 150 yards away, I can see his flashlight, but he might not be able to see me since much less light hits me and reflects back.

    Then we get into if the eye and brain can actually distinguish you from your surroundings. There are way too many variables to really go in depth, but on the few occasions I've had to go look for something in the woods in the dark, I can tell you that it is NOT easy! If you are simply standing in an open field then I would say that as long as the man isn't too far away, he should be able to see you. If you were in the brush behind the plants, it would be much more difficult.
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