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Physics Questions Help!

  1. Sep 14, 2013 #1
    1. The problem statement, all variables and given/known data

    Two point charges are distance d = 47.8 cm apart, They have equal and opposite charge, each with magnitude Q = 1.62 μC. The negative charge is on the left, and the positive charge is on the right. An electron (mass ##9.11\times 10^{-31}## kg, charge ##1.6\times 10^{-19}## C) is placed half-way between the charges.

    c) What is the force of the electron?

    d) What is the direction of the force on the electron?

    2. Relevant equations

    • ##E = \dfrac{kQ}{r^2}##
    • ##F = Eq##

    3. The attempt at a solution

    I just want to make sure if I'm right for both parts of the problem

    For part (c), I got this

    ##E = \dfrac{2kQ}{(\frac{d}{2})^2}##

    ##F = Eq##
    ##F = \dfrac{2kQq}{(\frac{d}{2})^2}##

    where

    ##d = \text{distance between the two charges before the electron is placed}##
    ##q = \text{charge of the electron}##
    ##Q = \text{point charge with given value}##

    By substitution, I got ##8.17 \times 10^{-14}## N.

    For part (d), I believe the answer is "right, toward the positive charge" since electron attracts with the point charge with positive sign.
     
  2. jcsd
  3. Sep 14, 2013 #2
    Looks good to me: I didn't check your calculator skill, but the physics seems right.
     
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