1Because of the difference in electric force experienced by like charges and unlike charges.
6 Answers
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1I think you might have read electrostatics.
Force between two charges is given by:
F=Kq1q2r2
Consider the case when both are positive
In that case F is positive.
Consider the case when the charges are opposite
In that F is negative.
Please do the calculations also to get it.
Now the two forces are differing in their signs.So it means that they are of opposite nature.
Swordfish is absolutely right.
You might have read in the textbooks that - is shown for attraction.So + should be for repulsion.
I think you have understood.
21QED (Quantum electrodynamics) suggests that charges interact through virtual (invisible) photons. I don't know the exact explanation of attraction, but repulsion is quite easy. Suppose you are on a boat and your friend is in another boat. If you have a volley ball and you throw it to your friend, then your boat will move backwards. When your friend catches the ball, the momentum of ball will push his boat backward too. On the whole, you are getting away from each other by throwing the ball to each other. All the charges keep emitting these virtual photons, and whenver a like charge comes in vicinity, this ball game starts between them, and they move away from each other.
For attraction, the momentum is in opposite direction (I don't think I am very clear here), so that when virtual photons are exchanged between unlike charges, it results in both of them moving towards each other.
However, it is best to assume for the time being that charge interaction is the natural way in which charges interact.
source : www.physicsforum.com
1Does reason of reason exist?
It is the property of the charges that like charges repel each other and unlike charges attract each other.These have been made so.It is their nature.
Now what about Subhodip's theory
If the charges emit photons then it means that proton and electron should also emit photons.I have heard and seen that atoms emit photons in the form of radiation when electrons are excited.What is the deifinition of photons?Light can be supposed to be made of photons.It is light.It is light.Then it means that electrons and protons emit light radiations.Then it means that when electron in a hydrogen atom is in ground state then it must emit radiations as it is in attraction with the protons.Then it means that electron should loose its energy .Then what will happen?After loosing energy the electron will keep on continuing closer to the nucleus.Then what will happen?At some instant of time it will strike with the nucleus.Then what will happen?The atom will become unstable.But atoms are stable.So it menas that the elctron does not fall into nucleus.Then it means that it does not loose energy.Then it means that it does not loose any photn.Then it means that electrons and protons are in an attraction without any ejection of photons.So Subhodip's theory fails here.Why is it not explaining this case of attraction between electrons and protons in atoms.So it means that this theory is wrong.
Dear Subohdip ,you should not accept the theories blindly,especially which are available on the internet,because they can be false.
So I think that we will have to accept that like charges repel and unlike charges attract.Thius is their nature.
If you want to ask why,then you should ask why does earth attract the moon?The answer will be gravitational force.If you ask why is this force there?Then the answer shouyld be that it has to be there,it were there and it will be there.Can any answer be given to this?No.Because this is the fundamental truth.Becuae there cannot be any reason of reason.
1my question is why does force between any two bodies exist?
You might want to read this - http://en.wikipedia.org/wiki/Fundamental_interaction