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Lifting Magnets Working Principle
Jun 27, 2017

Lifting Magnets Working principle

Working principle editor

When the core is inserted inside the solenoid, the core is magnetized by the magnetic field of the solenoid. The magnetized core also becomes a magnet, so that the magnetic properties of the solenoid are greatly enhanced by the superposition of the two magnetic fields. In order to make the magnet more magnetic, usually the core made of hoof. But pay attention to the hoof-shaped core on the opposite side of the coil, while clockwise, the other side must be counterclockwise. If the winding is the same, the magnetization of the two coils to the core will cancel each other, so that the core does not appear magnetic. In addition, the iron core made of soft iron, and can not do with steel. Otherwise, once the magnet is magnetized, it will remain magnetic for a long time and can not be demagnetized. The strength of the magnet can not be controlled by the size of the current, and the advantages of the lifting electromagnet should be lost.

Direction judgment edit

The direction of the magnetic field of the electromagnet can be judged by the ampere rule.

Ampere is a rule that the current and current excitation magnetic field of the relationship between the direction of the magnetic induction line, also known as the right hand spiral rule.

(1) energized straight conductor in the safety rules (ampere rule one): with the right hand holding the direct conductor straight, so that the thumb pointing to the current direction, four fingers pointing to the direction of the magnetic wire around the straight wire.

(2) the safety of the solenoid in the installation of the law (ampere rule two): with the right hand holding the solenoid, so that the four fingers bent in line with the current direction, then the thumb refers to the end of the power solenoid The N pole


The ampere rule of the linear current is also applicable to a small linear current. The toroidal current can be regarded as the composition of many small linear currents, and the direction of the magnetic flux intensity on the central axis of the toroidal current is determined for the linear current of each section. Superimposed to get the direction of the magnetic flux on the central axis of the toroidal current. The linear current of the ampere-order is the basic, the ring current ampere-order by the linear current ampere rule derived linear current ampere-order charge for the linear motion of the magnetic field is also applicable, then the current direction and positive charge movement direction The same, and negative charge movement in the opposite direction.


Under the inspiration of Oster's current magnetism experiment and other series of experiments, Ampere recognizes that the nature of the magnetic phenomena is a current that sums up the interactions involving currents and magnets into currents, The basic problem of the law of meta - interaction. In order to overcome the difficulties that the isolated current element can not measure directly, Amp carefully designed four experiments with zero and accompanied by careful theoretical analysis to arrive at the result. However, due to Ampere's concept of over-action of electromagnetic action, in the theoretical analysis of the two current elements imposed by the force along the connection assumptions, expect to comply with Newton's third law, the conclusion is wrong. The above formula is to abandon the wrong force along the connection of the hypothesis, the corrected result. It should be understood by the close-up point of view that the current element produces a magnetic field and the magnetic field exerts a force on the other current element.

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