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Homework Help: Direction of electric field

  1. Mar 7, 2008 #1
    but let say you have two charges + and - and they are 30 cm apart, why is it that when your finding the electric field strength in the midde the charges that the direction of the force of the - charge is in the SAME direction as the + charge.. Shouldnt it be opposite and unlike charges attract??
  2. jcsd
  3. Mar 7, 2008 #2
    The electric field originates from the +ve charge and flows to the -ve charge.

    The force on the -ve charge BY the +ve charge is directed towards the +ve charge.
    The force on the +ve charge BY the -ve charge is directed towards the -ve charge.

    A positive test charge between the two will experience a force described by the electric field lines--i.e. in the direction of the vector from the +ve charge to the -ve charge.

    I'm not sure what you were saying, but hopefully this clears some of it up.
  4. Mar 8, 2008 #3


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    If the two charges were side-by-side, then the field directions would be opposite.

    Now move one of the charges in a circle round to the other side of the test charge - can you see that its field direction will go round with it, so that the two field directions are now the same? :smile:
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