1. Not finding help here? Sign up for a free 30min tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Potential Difference, given E

  1. Nov 1, 2007 #1
    1. The problem statement, all variables and given/known data

    What is the potential difference between yi= -5cm and yf=5cm in the uniform electric field E = ( 20,000{ i } - 50,000 { j } )V/m?

    2. Relevant equations

    ∆V = V(sf) - V(si) = -∫ Es ds

    with the limits of the integral being sf and si

    3. The attempt at a solution

    I tried doing the integral, resulting in (E2)/2, and then multiplying proceding as so:

    E= √ (200002 + 500002) = 53851.64807
    (E2)/2 = 14500000 = x
    x |0.05,-0.05 = -{x(0.05) - x(-0.05)} = -{2[x(0.05)]} = -1450000 = incorrect

    any help?

    thanks!
     
  2. jcsd
  3. Nov 1, 2007 #2
    I think you're taking the integral as if it were E dE instead of ds (Compare with the case where if it were the integral of x dx, then the integral is x^2/2). E is a constant since it is "uniform", so you can treat it as a constant and pull it out of the integral. If you're only dealing with one dimension (along y), then the integral of E ds simplifies to E(Sf - Si).
     
  4. Nov 1, 2007 #3
    aaahh lol nice....yea that was my mistake...lol whenever i see the integral sign i jump to conclusions without looking at the second part

    thanks!
     
  5. Nov 2, 2007 #4
    well actually...i tried that and it didn't work:

    E = 53851.64807

    Sf-Si = 0.05 - (-0.05) = 0.1

    E * (Sf-Si) = 53851.64807 * 0.1 = 5385.164807 = Incorrect :(

    Any help?

    Thanks!
     
  6. Nov 2, 2007 #5
    I have only one attempt left. I noticed that I didn't put the negative sign there, but the computer would tell me to 'check your signs' if this was a sign issue...so i assume it isn't
     
  7. Nov 3, 2007 #6
    any help?
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?