Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Prove Voltage should be linear function of position

  1. Aug 3, 2003 #1

    avs

    User Avatar

    Giving that: V(x)=Cx
    Express the answer in terms of wire length L, battery voltage Vin the variable x and any numerical or physical constant. C should equal to 1.3594 which is the slope of my volage vs distance graph.

    This is what i got so far. Not sure if it is correct.
    V=iR -> V=(i*(rho)*L)/A so therefore my C is i(rho)/A and L=x

    Am i going in the right direction?
     
  2. jcsd
  3. Aug 3, 2003 #2
    Well, obviously C = Vin/L.
    So V(x) = Vin*x/L.
    I can't see what for you need the numerical value, or a graph.
    Is this really college level?
     
    Last edited: Aug 3, 2003
  4. Aug 3, 2003 #3

    avs

    User Avatar

    yea it's for a physics 2 lab.
     
  5. Aug 6, 2003 #4

    HallsofIvy

    User Avatar
    Science Advisor

    I'm puzzled by your titling this "Prove Voltage should be linear function of position" and then imediately saying "Giving (Given?)that: V(x)=Cx"

    If the problem is to prove something, then you wouldn't be "given" it!

    Since this is for a physics LAB, I suspect that you were asked to measure voltage versus length of wire in the laboratory, then graph the data. "Proving" (not in the mathematical sense) that voltage is a linear function of length is just a matter of observing that the points tend to lie along a line.

    Since you say that you have already done that and found that the slope of the line is 1.3594, you know that you can write V(x) as
    V(x)= 1.3594x+ V0 (V0 is the voltage when x= 0. If I understand your experiment correctly, that should be Vin.)

    You are asked to "Express the answer in terms of wire length L, battery voltage Vin the variable x and any numerical or physical constant."

    Okay, what is the voltage when x= L, then entire length of the wire?
    If you call that Vl, then you should have (Vl- Vin)/L= slope= 1.3594.
     
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook