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Homework Help: Energy Dissipation Across a Resistor

  1. Jul 7, 2012 #1
    1. The problem statement, all variables and given/known data
    A battery is connected across a uniform resistor R0. A sliding contact can move across R0 from x=0 to x=10cm at the right. Moving the contact changes how much resistance R is to the left of the contact and how much is to the right. Find the rate at which energy is dissipated in R as a function of x.

    2. Relevant equations
    Energy dissipated: PR=i2R
    Voltage is the same for resistors in parallel

    3. The attempt at a solution
    I tried to express R in terms of x and R0, but I got stuck. I honestly have no idea how to begin, or even if all of the equations that I wrote above are relevant to this question. Could someone please give me a hint that'll point me in the right direction? Thanks!
  2. jcsd
  3. Jul 8, 2012 #2


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    hi boredbluejay! :smile:

    isn't resistance proportional to length? :wink:
  4. Jul 8, 2012 #3
    I guess, but by what factor. >< I'm sorry, I'm really bad at this.
  5. Jul 8, 2012 #4


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    Gold Member

    You have two points on the x,R plane: (0,0) and (10,R0). With this, determine the linear relationship R = mx + b.
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