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Homework Help: Electric Force Field Tension

  1. Jan 31, 2010 #1
    1. The problem statement, all variables and given/known data

    The electric field between the plates of a parallel-plate capacitor is horizontal, uniform and has a magnitude E. A small object with a charge of -2.60 µC is attached to the string. Assume that the tension in the string is 0.350 N, and the angle it makes with the vertical is 10°

    What is the magnitude of the electric field?
    What is the mass of the object?

    2. Relevant equations

    E=Tsin(theta)/q

    3. The attempt at a solution

    E = (.350)(.1736)/-2.60x10^-6 = 23375 N/C

    So I got this, but how does it help me find the mass of the object? Please forgive me if it is simple but I am refreshing on physics as the semester just started last week ;)
     
  2. jcsd
  3. Jan 31, 2010 #2
    Hello octoshark.
    I agree with you on the first question.

    For the second, what forces are acting vertically?
     
  4. Jan 31, 2010 #3
    -PROBLEM SOLVED-

    I didn't realize it was as simple as T=mg/cos(theta) from the way my teacher worded it, it didn't make sense

    Answer: 35g
     
  5. Jan 31, 2010 #4
    Cool Beans
     
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