Horseshoe magnet

[1]: 3  Historically, they were a solution to the problem of making a compact magnet that does not destroy itself in its own demagnetizing field.

[1]: 2 [2] In 1819, it was discovered that passing electric current through a piece of metal deflected a compass needle.

These experiments culminated in William Sturgeon wrapping wire around a horseshoe-shaped piece of iron and running electric current through the wires creating the first horseshoe magnet.

[4] This would lay the groundwork for development of the electrical telegraph and the future of world-wide telecommunications for the next century and more.

[6] The shape of the horseshoe magnet also drastically reduces its demagnetization over time.

Horseshoe magnet with computed magnetic field lines. The two magnetic poles are in close vicinity, which concentrates the field lines and creates a strong magnetic field.
Magnetic fields of a horseshoe magnet visualized using iron filings.