In 1822, French physicist Arago and Lussac found that when an electric current passes through the wire, it can magnetization the iron block in the wire. This is actually the original discovery of the electromagnet principle. In 1823, Sturgeon also did a similar experiment: He circled 18 laps of copper bare on a U-shaped iron bar that was not a magnet rod, and when the copper wire was connected to the volt battery, the copper coil around the U-shaped iron rod produced a dense magnetic field, making the U-shaped iron rod a "electromagnet". This electromagnet on the magnetic energy than the permanent magnet can be magnified many times, it can suck up 20 times times heavier than its iron block, and when the power is cut, U-shaped iron bar is not able to absorb, and then become a common rod. The invention of Sturgeon electric magnets has led to a bright prospect of converting electricity into magnetic energy, which was soon spread across the UK, the United States and some coastal countries in Western Europe. In 1829, American electronics Henry had revolutionized the Sturgeon electromagnet device, replacing the bare copper conductor with insulated wires, so there was no need to worry about being short-circuited by copper conductors. Because the wires have insulating layer, they can circle tightly around together, because the more dense coils, the stronger the magnetic field, thus greatly improving the ability to convert electricity into magnetic energy. By the year 1831, Henry produced an updated electromagnet, which, though not large, could suck up 1 tonnes of iron. The invention of electromagnetic iron also makes the power of the generator greatly improved.