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Homework Help: Calculating electric field

  1. Mar 14, 2010 #1
    1. 30.P49.jpg

    I am then asked to pick the magnitude and direction of E at each point. For all points, I can correctly deduce the direction because the E field points in the direction of decreasing potential. However, what are they doing to calculate the magnitude here? I know the magnitude is 500V/m for A, and I could deduce the correct answers for the rest of the points relative to A.

    2. V = U/q = Ed

    3. Since I'm not given the charge of a particle at those points, I must need to use some value for d to compute E since V is known for each point. But what d do I use?
  2. jcsd
  3. Mar 15, 2010 #2


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    Homework Helper

    You get the component of the field strength from the potential difference between the nearest points divided by the distance between them: E=(V1-V2)/d. At A, E = (75-50)/d = 500 V/m.

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