i wonder why two point charge whose magnitude 0 and +q(or smt different from zero charge) exert a coloumb force to one another
.formula says there shoud be no force acting to each other(because of multiplication q1.q2=0) but there is an atraction between them .
if this force exist what the magnitude is.

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 Quote by cherev i wonder why two point charge whose magnitude 0 and +q(or smt different from zero charge) exert a coloumb force to one another
They dont exert a Coloumb force on one another because, as you state below, q1*q2=0

 .formula says there shoud be no force acting to each other(because of multiplication q1.q2=0) but there is an atraction between them .
no, there isn't.

 if this force exist what the magnitude is. thanks for your reply..
magnitude = 0
 The electromagnetic interaction cannot occur between a charged and a neutral body. What says there is an attraction between them? Does it explicitly say this attraction is electromagnetic?

but why neutral piece of paper and charged plastic rod attract each other
 Induced dipoles in the paper. The plastic rod (charged negative, IIRC) pushes electrons away from the near side of the paper, resulting in a shift of the charge centers with the positive charge center nearer the rod. This means the net force of attraction between the rod and the positive charges in the paper is slightly greater than the net force of repulsion between the rod and the negative charges of the paper. Hence, an overall net force.

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 Quote by cherev but why neutral piece of paper and charged plastic rod attract each other
those are not point charges.
 but ı have seen a figure on serway physics which shows atractive force between neutral and positive charged point charge on page 786
 I'm looking at p786 and there isn't a diagram of point charges. I've got 6th edn, whats the figure number? Is it P25.30?
 ı have 5th edition and its may be different because I am not in u.s.a but figure is showed in gauss law
 what number? There's a lot of figures in the section Gauss' Law!