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Math Help - Using Graphical Techniques to find values

  1. #1
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    Using Graphical Techniques to find values

    Hi there,

    was looking for some advice and assistance on a particular question if at all possible. I'm looking to solve the following:



    results were collected in an experiment to find the relationship between the luminosity (I) of a lamp and the voltage (V). The law is thought to be of the type I=aVn

    Now I need to plot Log I (Vertically) against Log V (Horizontally) and find the values of A and N. The data is below.

    V 40 60 80 100 120

    I 5.1 26.0 82 200 414


    Any tips on how I go about solving this will be greatly appreciated.

    I'll look forward to reading your replys,

    Thanks
    MrMagoo
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  2. #2
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    Re: Using Graphical Techniques to find values

    Starting with your equation I=aV^n

    Take the log of both sides

    \log I=\log(aV^n)

    Sort out the right hand side a bit

    \log I=\log(a)+\log(V^n)

    and a bit more

    \log I=\log(a)+n\log(V)

    \log I=n\log(V)+\log(a)

    You've now got it in the form Y=mX+c.

    Are you OK from there?
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  3. #3
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    Re: Using Graphical Techniques to find values

    Thank you very much, thats a great help. I shall give it a go.
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  4. #4
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    Re: Using Graphical Techniques to find values

    Would anyone be able to advise me with what I need to do with the log functions?

    now its in the form of y=mx+c I assume I create my graph with the results obtained and then use this to find the values of m and c which equate to a and n.

    In summary do the log functions change anything and if they do in what way.

    Many thanks for any help received.
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