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Inductive coil core science introduction

First, the basic concept of magnetism:
What is magnetic? The so-called magnetic property is that the object is placed in a magnetic field of uneven size and is subjected to a magnetic force. Among the same inhomogeneous magnetic fields, the magnetic strength of the object is determined due to the magnetic orientation and magnitude of the object. Because in theory it can be said that any object is magnetic, any substance will be subjected to a certain degree of magnetic force in an inhomogeneous magnetic field. In nature, iron, nickel, cobalt and other substances will produce a strong mutual attraction force under certain circumstances. These substances are called magnetic, and they are transformed into magnetic processes. We call them magnetization. . As long as it can be magnetized or attracted to a magnetic substance, we call it a magnetic substance or a magnetic medium.
The magnetically strongest part of the magnet is called the magnetic pole, so the magnetic pole can be divided into two levels, the south pole S and the north pole N. Experiments have shown that the same magnetic poles will repel each other, and the different magnetic poles will attract each other. In daily life, we call it homosexual repulsion and opposite sex attracting.

Second, the unit of the magnetic core of the inductor
The magnetic induction is the physical strength of the magnetic field and the direction, and the unit is expressed by T. The basic physical quantity used to describe the magnetic field is called the magnetic induction intensity, which is usually expressed by B. The size of B is equal to the magnitude of the magnetic field force of a straight wire that is 1 m long and a current of 1 A perpendicular to the magnetic field. The formula is: B = F / IL.

Third, the electromagnetic application of the inductor core
1. Self-inductance: When the magnitude of the current in the conductor changes, the size of the surrounding magnetic field will also change accordingly. At this time, a change in magnetic flux will occur, and a corresponding induced electromotive force will be generated in the conductor because The electromotive force blocks the change of current in the conductor. The electromotive force at this time is the self-induced electromotive force. We call this phenomenon a self-inductance phenomenon.
2. Mutual inductance: When the current inside the coil changes, the induced electromotive force will be generated in the other coil next to it. We call this phenomenon mutual inductance. Mutual inductance is a very common phenomenon of electromagnetic induction. It does not occur between two similar coils, but also between two similar circuits.

Fourth, electromagnetic coil core core material classification
1. Manganese zinc:
Composition: iron oxide 70%, MnO 20%, Zn: 5%, several other metal oxides
Resistivity: approximately 10 Ohms-cm
2. Nickel and zinc:
Composition: ferric oxide 45%, NiO 25%, Zn 25%, several other metal oxides
High resistivity, up to 10*7 power Ohms-cm
Main uses: filters, inductors
3. Handan steel:
Very high initial guidance, up to 50,000~60000
Very low resistivity, generally used for low frequency inductors
4. Iron powder core:
Very fine iron powder bonding of organic materials
The magnetic permeability is between 15~80
5. Iron silicon aluminum
Composition: iron 80% silicon 9% aluminum 6%, several other metal oxides
Low magnetic permeability between 25 and 125
6. Iron nickel:
Composition: iron 45%, nickel 50%, several other metal oxides
The magnetic permeability is slightly higher than that of iron silicon aluminum, and the loss is also lower than that of iron silicon aluminum.
7. Ferrite
Composition: ferric oxide and one or several other metal oxides
Low resistivity for low frequency inductors

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