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Reflection question

  1. Oct 23, 2004 #1
    Need some help on a practice physics problem.

    You need to place a mirror on the left wall, so that the reflected light from the bulb exactly fills the right wall.

    ceiling
    _________________________
    | |
    | |
    3m | |
    | 0 |
    | |
    | |
    _________________________
    4m
    - the light bulb is 1m away from the left wall, it looks like it is centered.
    a. what is the proper height of the mirror?
    b. how far below the ceiling should the edge of the mirror be?
    c. a 10cm tall screen to the right of the bulb from illuminating the right wall directly, what is the height of the screen's shadow on the right wall?

    how I've approached the problem thus far: I started by stating that the angle that the top right corner makes with the mirror's top should be theta reflective and the other angle to the source from the mirror would be theta incidence due to the law of reflection. I'm lost as to where to go from here.
     

    Attached Files:

  2. jcsd
  3. Oct 24, 2004 #2

    ehild

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    Homework Helper
    Gold Member


    And you know that theta reflective equals to theta incidence.
    You can find the edges of the mirror easily by connecting the top (bottom) of the wall and the mirror image of the source by straight lines. See the figure attached.

    ehild
     
    Last edited: Jun 29, 2010
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