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Electric force particles

  1. Feb 22, 2008 #1
    - the electric force is inversely proportional to the square of the separation r between the particles and directed along the line joining them.

    - is proportional to the product of the charges q1 and q2 on the two particles.

    i dont understand wut does that mean, can someone plz explains it to me n simple terms
  2. jcsd
  3. Feb 23, 2008 #2


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    Staff: Mentor

    What specific words are you having trouble with? Start at the beginning of the first statement and tell us where you first start to have trouble.
  4. Feb 24, 2008 #3
    F = (K * q1 * q1)/r^2

    K = 9 * 10^9 N m^2/c^2 (for vacuum and air)

    If q1 and/or q2 increase, force is too
    if r increase, force decreases

    --------------------- example 1
    q1 = 1 c
    q2 = 1 c
    r = 1 m

    F= (9 * 10^9 * 1 * 1)/1^2 = 9 * 10^9

    ------------------- example 2
    q1 = 2 c
    q2 = 1 c
    r = 1 m

    F= (9 * 10^9 * 1 * 2)/1^2 = 9 * 10^9 * 2

    --------------------- example 3

    q1 = 1 c
    q2 = 1 c
    r = 2 m

    F= (9 * 10^9 * 1 * 1)/2^2 = (9 * 10^9)/4
    Last edited: Feb 24, 2008
  5. Feb 24, 2008 #4
    (1) There is something called electric force which only exists when electric charges are under consideration. With no electric charges there is no electric force and to have an electric force one must first procure electric charges.

    (2) It was found that an electric force exists minimally betwen two electric charges which we can conveniently call q1 and q2. The letter "q" usually connotes electric charge.

    (3) When we place two charges next to each other, it was found that one principal factor that affected the electric force, was the relation between the two charges: q1*q2, and not q1 + q2, or q1 - q2, or q1/q2. The size of the electric force varies directly with the quantity of electric charges.

    (4) To find whether this electric force is local or non-local, experiments were performed which eventually localized the electric force to be in the immediate vicinity of the electric charges. Everytime the charges q1 and q2 were placed a distance, r apart and the force F calculated, it was found the electric force diminished, the further the charges were apart, and conversely, the closer the charges were together the greater the electric force became. However the electric force varied not with 2r, r-1, or 1/r, but with 1/r*r. This is called an inverse proportionality (1/X) as opposed to a direct proportionality (X).

    (5) The electric force F is proportional to q1*q2/r * r. This number gives a local value per area between the charges, which is directly proportional to the electric force.
  6. Feb 25, 2008 #5


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    Science Advisor
    Homework Helper

    "inversely" means "1/…"
    "separation" means distance
    So altogether it's:
    :smile: Force = (constant x q1 x q2)/distance-squared. :smile:
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