Principle after the solenoid is energized to produce a magnetic field like a bar magnet. Circle graph for magnet wire section, point out on behalf of the current screen, fork representative inflow screen; the arrow attached oval circle is the magnetic field lines. When direct current through a conductor creates a magnetic field, while a similar magnetic bar magnets made through the solenoid (Solenoid) conductor will be generated. In the center of the solenoid a magnetic substance is added to this magnetic substance is magnetized to achieve the effect of strong magnetic field. Generally Jiang million bags magnets, electromagnets and the magnetic field strength generated by direct current size, number of turns and the center of permeable material related to the electromagnet in the design and selection guide will focus on the distribution of iron coil material, and use DC magnetic field strength to control the size. However, the coil material having a resistance to limit the size of the field magnet solenoid limited supply tools that can be derived, but with the discovery and application of the superconductor will have the opportunity to break the current limit. Thirties late 1930s, alnico magnet successful development, it makes possible large-scale application of the magnet. Fifties fifties, there barium ferrite magnet, a permanent magnet not only reduces the cost, scope of application of permanent magnet materials in turn broaden the high-frequency fields. Sixties sixties to low-cost supply of toys with magnets, samarium cobalt permanent emergence, for the application of magnets has opened up a new era. So far, the rare earth permanent magnet has experienced first-generation SmCo5, the second generation of precipitation hardening Sm2Co17, third generation Nd-Fe-B permanent magnet materials. Ferrite magnets are still present, the largest amount of permanent magnet materials, NdFeB magnets but has greatly exceeded the value of the ferrite permanent magnet materials, NdFeB magnet production has become a major industry. Warring States Period magnetic phenomena found our ancestors have accumulated a lot of understanding in this area, often encountered in the search for iron ore magnetite, that magnet (the main ingredient is iron oxide). These findings have long been documented down. "Tube" of several articles in the earliest records of these findings: "the mountains are a magnet who, under which a bronze." Which tool magnets, magnetic Xin Tong new magnet provided by the Dongguan City Tong Xin magnetic Limited . Xin Tong, Dongguan City, the new magnetic Limited (www.dgxtxmagnet.com/) is Dongguan, Guangdong, magnetic leader, over the years, the company is implementing the scientific management, innovation and development, the principle of honesty and trustworthiness, and satisfy customer needs. In the new Tong Xin magnetic leadership with the staff warmly welcome all inquiries to discuss, with new magnetic Tong Xin a better future.