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Imagine that you are looking at yourself in a mirror mounted on a wall

  1. Nov 11, 2011 #1
    1. The problem statement, all variables and given/known data
    Imagine that you are looking at yourself in a mirror mounted on a wall. From where you stand, you are able to see from the top of youre head down to the top of your shoulders.

    Suppose you were to back away from the mirror. Would the amount of your body that you see in the mirror increase, decrease, stay the same. Explain. Include a diagram as part of explanation.


    2. Relevant equations



    3. The attempt at a solution

    I know that the amount I would see in the mirror would increase, but I'm having a hard time explaining why, further more i dont have a clear idea on what my diagram should be. I think it may have to do with the focal point and the image, so any help would be nice thanks.
     
  2. jcsd
  3. Nov 11, 2011 #2
    Re: Mirrors

    Let the person be a certain distance from the mirror. Consider a ray of light from the top of the head being incident on the mirror. How will this be reflected?

    Now let the person move further away from the mirror and repeat the process.

    The only principle to be used is 'angle of incidence = angle of reflection'.
     
  4. Nov 11, 2011 #3
    Re: Mirrors

    You stand in front of the mirror at any distance.
    Light from the top of your head travels to the mirror and is reflected into your eye.... that is how you see the top of your head in the mirror.
    Light from your feet travels to the mirror and is reflected into your eye.... that is how you see your feet in the mirror.
    Can you sketch this and see how long the mirror is (and how far the bottom of the mirror is from the floor?)
    As grzz says.... you only need 'angle of incidence = angle of reflection'
     
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