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Determine value of the resistance of the resister

  1. Feb 13, 2009 #1
    1. The problem statement, all variables and given/known data

    1.How do you determined( calculate )the value of the resistance of the resister by looking on a graph?

    2. Relevant equations

    3. The attempt at a solution
    I have data which includes a graph of Current in Amps volts for 47, 60 and 100 omega

    Current (Amps) 47Ω Voltage (Volts) 68Ω Voltage (Volts) 100Ω Voltage (Volts)
    0.01 0.5 0.6 1.6
    0.02 0.8 1.3 2.5
    0.03 1.3 2.1 3.3
    0.04 1.8 3.0 4.6
    0.05 2.3 3.5 5.7
  2. jcsd
  3. Feb 13, 2009 #2


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    Homework Helper

    Re: Lab

    Compare V = RI
    with y = mx + b
    Obviously the y-intercept is zero. The graph should have V on the y axis and I on the x axis. Then the slope will turn out to be the resistance. Draw a line of best fit through the data points and find the slope.
  4. Feb 13, 2009 #3
    Re: Lab

    So you know that resistivity and resistance are properties of any particular resistor.

    The equation you listed V=IR is correct assuming that the resistor doesn't heat up significantly.

    If you take a closer look at V=IR you'll notice that current is proportional to voltage, and that current and voltage are equivalent by some constant resistance value. Well that's just a line!

    We can think of it like this:

    V(I) = RI sort of like we think of y(x) = mx

    So your resistance value is just the slope of the voltage vs. current graph.

    Any of this help?
  5. Feb 14, 2009 #4
    Re: Lab

    so you find the slope then that is the resistance value? in this case the y= mx = b , then the mx is the resistance value?
  6. Feb 14, 2009 #5


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    Staff Emeritus
    Science Advisor
    Homework Helper

    Re: Lab

    No, "m" is the resistance value, since it is the slope.
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