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    Hi all,

    Please help me on voltage-length graphs whilst trying to calculate the resistivity of a material.

    In Physics, I did an experiment on calculating the resistivity of a material by altering the length of the wire.

    I have calculated the gradient of the graph, however, I am not sure of what this actually tells me? My educated guess is that it is the value of (V/L), but I'm not sure.

    Could someone please enlighten me on this?


    Thank you very much!
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    Im not sure about this (since I did alternative to practicals) but if we look at the formulae:
    1. Resistance = (resistivity of the material X length of the wire)/ cross sectional area of the wire
    2. Voltage= resistance X current (V=IR)

    Since you drew a graph of Voltage against length, we need voltage on one side and length on the other

    V=IR
    R= V/I - valid.

    R= pl/A
    V/I= pl/A
    V= (pl X I)/A (in words, voltage = resistivity into length of the wire into the current divided by the Area)

    Since y= mx + C (the gradient of a straight line)
    the gradient of a Voltage-length graph should give you (pXI)/ A i.e resistivity into current divided by Area.

    I hope you can understand how I got the gradient (The i and the l look very similar, sorry about that.)
 
 
 
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