1. The magnet poles are repelled by the magnetic field. A magnetic field can work at a distance, via the inverse square law, which is why the repulsion is greater when they get closer.
2. Electrostatic force is caused by charged particles that attract or repel each other. Like charges repel and unlike attract.
3. Like 1 there is a magnetic field that produces an attractive force between the magnet and the iron that it is near.
4. This is the same question that people have been pondering for hundreds of years. Gravity is the observable force between to objects that have mass that cause them to be pulled toward one another. Once again it has fields and seems to have no polarity, meaning that gravity cannot repel. How it is produced is still unknown. Is it a subatomic particle? Is it built into the other subatomic particles? We are not sure yet.
There are four types of forces that exist in nature, called forces of nature, "gravity", "electrostatic" and the weak and strong nuclear forces...... it is proposed that these can be generalized as different forms of one force, a unified force. So far no complete theory of unification exists..... At their nature, they r rather enigmatic so it is impossible to explain them completely
All is fine......But if we were to look at our friend's question more from a philosophical view point......Why should the so-called north pole repel another north pole...??I mean how would a North pole "know" that there is another north pole that it has to repel, when brought nearer...? What is polarity...?
Mr. My_Books....These questions ghost me too....I tried to find little salvage in Solid State Physics (SSP)...but coming from a pure electronics background I could'nt quite understand.
There are certain models proposed for atomic arrangement and the "Electron-cloud" that is shared among the core atoms....and stuff like that. Some purticular orientations yeild certain magnetic and electric properties to matter......From SSP's point of view, matter can be broadly classified as Ferromagnetic, ferrimagnetic, diamagnetic and paramagnetic. there are certain sub-classifications aswell......
I guess you will find reading SSP little informative.
Sai
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Ofcorse Talking about gravity.....there cannot be better book than our famous Stephen Hawking's "A brief History Of Time". He explained ina very lucious manner what is gravity....and related stuff.
There is yet another wonderful book..."Einstein's Universe"-by Nigel calder. Run little google and you shall see what Iam talking about...!!