We have referred to some magnetic materials when we tell about the magnetic source, electromagnetic induction and magnetic devices.
Practical application. In fact, magnetic materials have been widely used in various aspects of traditional industries.
For example, if there is no magnetic materials, electrical becomes impossible, because the power to use generators, transmission to use transformers, power machinery to use motor, telephones, radios and television sets will be used in speaker. Many instruments are used in magnetic coil structure. These are already talking about other contents.
Application of magnets in medicine
Pigeon lovers know, if the dove fly to hundreds of miles away, they will automatically. Why do pigeons have such a good ability to recognize the house? Pigeons are very sensitive to the magnetic field of the earth. They can find their own home with the change of the earth's magnetic field. If the dove head tied to a magnet, the dove will trek. If the pigeons were flying over the radio tower, the strong electromagnetic interference would also make them lose their way.
In medicine, using nuclear magnetic resonance diagnosis of human abnormal tissue, diagnosis of disease, this is we are more familiar with the nuclear magnetic resonance imaging technology, its basic principle is as follows: the nucleus of an atom with positively charged, and spin motion. In general, the arrangement of the nuclear spin axis is irregular, but when it is placed in an external magnetic field, the orientation of the nuclear spin space is from disorder to order. The magnetization vector of the spin system is gradually increasing, and when the system reaches equilibrium, the magnetization reaches the stable value. If the nuclear spin system is under the action of the external effects, such as the frequency of the RF excited nuclear can cause resonance effect. After the cessation of the RF pulse, atomic nuclear spin systems have been intensified, unable to maintain this state, will return to the magnetic field of the original arrangement of release at the same time, a weak energy to become a radio signal, to the many signal detection, and make the spatial resolution, is the movement of nuclear distribution image. Nuclear magnetic resonance is characterized by the flow of liquid does not produce a signal called the flow effect or the flow of the blank effect. So blood vessels are gray and white tubular structures, and blood is no signal of black. This makes it easy for blood vessels to be separated from soft tissues. The normal spinal cord is surrounded by cerebrospinal fluid, the cerebrospinal fluid is black, and the white dura mater is the fat, and the spinal cord is displayed as a strong signal structure. Magnetic resonance imaging has been applied to the imaging diagnosis of the whole body system. The best effect is the brain, and the spinal cord, heart, joints, bone, soft tissue and pelvis, etc.. On cardiovascular disease can not only were observed in each chamber, vascular and valvular anatomic changes, but also for ventricular analysis and qualitative and semi quantitative diagnosis, multiple sections, high spatial resolution, showing heart and the panorama of lesion, and relationship with the surrounding structures. Compared with other X-ray imaging, echocardiography, radionuclide and CT examination.