Final answer:
Magnet B is stronger because it can hold more steel paperclips. Rubbing a paper clip with a magnet makes it magnetized, and it will attract another paper clip. Magnetic properties differ between ferromagnetic and diamagnetic materials, and free-floating magnets align with Earth's magnetic north pole.
Step-by-step explanation:
If magnet A can hold 3 steel paperclips and magnet B can hold 5 steel paperclips, magnet B is stronger since it can hold more paperclips, which indicates that it has a greater magnetic force or magnetic field strength.
Rubbing a permanent bar magnet along a paper clip magnetizes the clip, and when brought near another paper clip, the second one will experience an attractive force because the first paper clip turns into a magnet with a north and south pole, creating its own magnetic field which exerts a force on the nearby clip.
Repeatedly rubbing the paper clip with the magnet increases its magnetization, making it more strongly attract the other paper clip. The paper clip that has been rubbed becomes magnetized, with its atoms and electrons aligning to create a magnetic field, whereas the untouched paper clip remains non-magnetized with randomly oriented magnetic domains.
When a knitting needle or a metal object is rubbed with a magnet, it can attract the paper clips as it is temporarily magnetized in the process. Similarly, ferromagnetic materials like iron have domains that can be aligned to create a magnet, but diamagnetic materials like lead have a much weaker and opposite response to a magnetic field. On Earth, a freely rotating magnet will align such that its north pole points to the magnetic north pole, which is actually a geographic south.
If two magnets repel each other, it indicates that the like poles (either both south poles or both north poles) are facing each other, as opposite poles attract and like poles repel.