Magnetic Fields, Magnetic Forces, and Electromagnetic Induction

Magnetism and electricity are deeply connected aspects of a single phenomenon, electromagnetism. A magnetic field is a region of space in which a magnetic force can be felt, produced by permanent magnets and, crucially, by moving electric charges. Every magnet has two poles, called north and south, and like poles repel while unlike poles attract. Unlike electric charges, magnetic poles cannot be isolated: cutting a magnet in half produces two smaller magnets, each with its own north and south pole.

Magnetic fields are represented by field lines, drawn from the north pole to the south pole outside a magnet and closing on themselves to form continuous loops. The lines never cross, and their spacing indicates the strength of the field, with closely spaced lines showing a strong field. The str