What are the conditions in which bar magnets repel or attract?

Answer 1

Because that's how magnetism works.

It's not really an especially satisfying answer, but really some things just are the way they are because they are that way.

We can use Maxwell's equations to describe in great detail how magnets (and electricity; the two are connected) work, but that's how, not why.

Answer 2

The standard North and South Pole explanation does not satisfy me. Yes, like poles repel and unlike poles attract but that doesn't explain the actual mechanism that causes the attraction or repulsion. I think that there is a similarity between a magnet and a tornado. If two tornadoes both rotating clockwise approached each other they would push each other away like gears grinding against each other. On the other hand if one tornado was rotating clockwise and the other counterclockwise they would not repel because they would be like gears meshing properly. So they would not repel but what then would cause them to attract. There are many forms of matter and energy in space, it is not empty. All these forms of matter and energy are not sitting still; they are moving and bumping into each other, pushing on the tornadoes. Two things that are not pushing against each other will be pushed together by all the other pushing forms of matter and energy in space. Also, a whirling tornado creates a partial vacuum inside the tornado which will enhance the forces pushing them together. A tornado is also called a vortex.
An electromagnet is usually made by wrapping insulated wire around an iron core and pushing electrons through the wire by connecting a battery or power source. This is very similar to a tornado or vortex but it is a vortex of rotating electrons. The rotating electrons in the wire will also stimulate the rotating electrons in the iron atoms. My guess is that the rotating electrons will create a partial vacuum of negatively (and probably positively) charged particles inside the vortex of rotating electrons. The external pushing forces in space will push against the magnets until their rotations in the electro magnets line up and no longer grind and push against each other i.e. like poles repel and opposite poles attract. They are just filling a vacuum!

This suggests a possible mechanism that better explains what happens with magnets and satisfies my curiosity more than a rule that says like poles repel and unlike poles attract. It may not fully explain the cause but I think it's closer to the actual mechanism.

The polarity of magnets causes them to repel and attract. Magnets normally have two ends, they are called north pole and south pole. Like poles repel and unlike poles attract. So, a north pole and north pole would repel each other, and a north pole and a south pole would attract each other.

Answer 3

Normaly ,the atoms within a material are natural having an equal number of electrons(-) and protons(+) however friction bettween certain materials cause electrons to move from one material to the other.when electrons are added to a material the material has a negative charge from a material the material has a positive(+).Electrical charges casued by friction are called static electricity .Materials with like charges repel each other materials with unlike charges attract each other .

Answer 4

Well the conditions are north and south. The north and north repel, same as the south and south.However, north and south attract eachother.

Answer 5

Opposite poles attract, like poles repel, either pole attracts unmagnetized ferromagnetic substances and (weakly) repels diamagnetic substances.