The hard drive uses two important principles about the magnetic fields. :: Computer Science

The ponderous drive uses two classic principles about the magnetic fields. When we write entropy onto the hard drive Cit uses the uprightness of electromagnetic induction and some material is magnetic.The hard drive uses two important principles about the magneticfields.When we write data onto the hard drive it uses the honor ofelectromagnetic induction and some material is magnetic.When we read data from the hard drive, it uses the Lenzs law.How hard disk drive worksFirstly we should know the two important part of the hard disk drive,1. platters and mediaWe put all of the data onto the platters. They are inside of the harddrive. There are several pieces of platter in the hard disk drive,maybe three or four. They are made of special material. The materialmust be strong and light. Because there are high whirling rates, whenthe hard disk drive working. Traditionally, people often use aluminumbecause it is a light material. But today, most platters are made frommaterial correspo nding glass or ceramic composite. These light, strongmaterials have a very low thermal expansion, and compare to aluminum.They washbowl withstand higher forces. So the platters can run faster.Older hard disk drive can only run at 3600 to 5200 rpm. Todays onescan run7600 to 10000 rpm.There is a layer of magnetic material on the surface of the platters.Today a thin-film media is used here. Thin-film media is a microscopiclayer of pure metal bonded to the substrate surface through an meantimelayer. Because the distance between head and platters is very small(about 10 micro inches), but they can not touch with each other. Sothe thin-film media is very immediately and is coated with a protective layerto help survive head crashing.2. the arm and read and write headThe arm that holds the read/write heads is controlled by the mechanismin the upper-left corner, and is able to move the heads from the hubto the edge of the drive. The arm and its movement mechanism areextremely light and fas t. The arm on a natural hard-disk drive canmove from hub to edge and back up to 50 times per second. It is hardto believe. But it is the truth.Simply, The read and write head is a ferromagnetic core. It canproduct a variety magnetic fields through a variety current to be ableto write data onto the media in ASC2. And also can product varietycurrent though inducing the variety magnetic field on the surface ofthe platter to read data from the hard disk drive.