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Homework Help: Excel graphing problems with a Physics lab

  1. May 1, 2012 #1
    1. The problem statement, all variables and given/known data

    I have two columns of data to graph from a lab we did on spherical lenses. The instructor showed a quick and dirty sketch of what our graph should look like - a decreasing curve. My data plots as an increasing linear graph. If I flip the x-axis data top to bottom I can get it to look like the instructor said it should, but I'm kinda stumped. Any suggestions? I can supply the data if needed.

    2. Relevant equations

    3. The attempt at a solution
  2. jcsd
  3. May 2, 2012 #2


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    Homework Helper
    Gold Member

    Hello BrewDaddy,

    Welcome to Physics Forums!

    If one column is for the x-axis and the other column is for the y-axis, do not choose a "Line" chart in Excel. Doing so will plot the column linearly, with equally spaced points on the x-axis, which is not what you would want in this case (it would essentially ignore your unique x-axis data).

    Instead (if you have your own x-axis data), use the "Scatter" plot option. That lets you plot (x, y) data points. You can still connect the data points with lines if you want.
  4. May 2, 2012 #3
    Thanks for the welcome! I have already tried the scatterplot method, but it still gives me the linear graph. I'm starting to think that the instructor was mistaken in his sketch of what the graph should look like - maybe he got mixed up with the graph from a different lab - we've done quite a few of them. I'm going to give it a shot the old fashioned pencil and graph paper way and see what I get. If I still get the same result I'll post the data and see if anyone can come up with any ideas. It's only 20 data points or so.

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