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Homework Help: Focal length of a concave mirror.

  1. Feb 13, 2008 #1
    1. The problem statement, all variables and given/known data

    Focal length of a concave mirror.
    This was an experiment, done in class.

    I was required to collect a light globe:(of course with a power source) for the object, paper:screen/image, and a concave mirror.

    I created the images, of the globe filament, to the screen, and measured.

    I took 5 trials of V and U, where; U=Object distance, and V= Image distance. The results were; 1.)V=25.0, U=38.0
    2.)V=22,0, U=47.0
    3.)V=20.0, U=57.5
    4.)V=18.5, U=75.0
    5.)V=18.0, U=88.5

    From here, I could use the graphics calculator (1/v for y-axis, and 1/u for x-axis), or 1/f=1/v+1/u for each and average them.

    Question 1.: What is the graphical method (calculator.)?
    Question 2.: What is the Mirror equn method?
    Question 3.: Why is the graphical method more accurate, than 1/f=1/v+1/u?

    2. Relevant equations

    3. The attempt at a solution

    1.) stat, 1/u for list1, 1/v for list2, GRPH, GPH1, X, Copy, Menu, GRAPH,
    Y=-1.0522075X+0.067, Enter, G solv, Xcal- when Y=0, Ycal- when X=0.

    Then f=1/yintercept and f=1/xintercept for focal length.

    2.) average values (of 1/f=1/v+1/u).
  2. jcsd
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