Why do opposite poles of a magnet attract each other? What is the reason behind it? What happens at the atomic level when opposite poles attract each other?
The reason that two magnets will attract or repulse each other has to do with the poles of the magnet. A magnet has a north and south pole. When allowed to rotate, the north pole end of a magnet will point in the direction of the North Pole. Conversely the south pole end of the magnet will face toward the South Pole. Energy emanates in invisible lines from the polar ends of a magnet, creating a field of force that causes two opposing poles to pull together and like poles to push apart when facing one another.
Magnets create a field of force at each end due to negatively charged electrons that are in motion. These fields of force have imaginary lines of flux that move the electrons from one end of the magnet to the other. The attraction or repulsion of two magnets is dependent on the poles and the moving of electrically-charged particles. This causes magnets at opposite poles to attract one another.