MARTYN F. CHILLMAID / SCIENCE PHOTO LIBRARY MARTYN F. CHILLMAID / SCIENCE PHOTO LIBRARY
Magnetic repulsion. The iron filings sprinkled on a dark blue background reveal the shape of the repulsive magnetic field between two magnets (not seen, below paper). The filings show the repulsion as field lines arcing away from the ends of the magnets. Bar magnets have a north and a south pole. Unlike poles attract each other, whereas like poles repel each other. The magnetised filings align in thin arcing lines due to the interactions between them, even though the magnetic field itself is continuous.
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