In 1822, the French physicists Arago and Lussac found that when iron block is when the current through the winding, it can make iron magnetization in the wound. This is actually the electromagnet principle was originally found. In 1823, the sturgeon also did a similar experiment: he is a u-shaped iron rod is not a bar magnet around lap 18 copper wires, when the copper wire and the Volta battery switched on, around a u-shaped bar of copper coils which generate intense magnetic fields, which makes a u-shaped iron rod into a "magnet". This magnetic energy than in the electromagnets pm many times larger, it can lift 20 times heavier than it's a piece of iron, and when the power is cut off, u-shaped iron rod could not get any piece of iron absorption, again a common iron rod. Sturgeon's electromagnet invented so that people can see the bright prospects of electrical energy into magnetic energy, this soon in the United Kingdom, the United States and some Western European coastal countries to spread. In 1829, the American electrical Henry sturgeon electromagnet device for a number of innovations, instead of bare copper conductors of insulated wires, so you don't have to worry about copper wires too close to short circuit. Due to wire insulation, you can circle around together tightly, more intensive due to coil, the magnetic field produced by the stronger, this will greatly improve the capacity of electrical energy into magnetic energy. By 1831, Henry developed a newer magnet, while its volume is not large, but it can lift 1 ton block of iron. Invention of the electromagnet that power generators may be greatly improved.