& nbsp; 1. What is a magnetic field?
& nbsp; & nbsp; & nbsp; & nbsp; Answer: Around the magnetic pole or any current loop, and inside and outside the magnetized object, there is a magnetic effect on the magnetic needle or moving charge, which is called magnetic field. It is similar to electric field and has the characteristics of force and energy.
& nbsp; & nbsp; & nbsp; & nbsp; (2) What are insulating materials? What are the main types?
& nbsp; & nbsp; & nbsp; & nbsp; Answer: Insulating materials are also called dielectrics. Popular talkInsulating materialsIt is the material that prevents the current from passing through it, that is, the non-conductive material. Commonly used insulation materials are: gas: such as air, sulfur hexafluoride and so on. Liquids: such as transformer oil, cable oil, capacitor oil, etc. Solid materials include two types: one is inorganic insulation materials, such as polyimide film, mica, mica board asbestos, electric ceramics, glass, and the other is organic materials, such as paper, cotton yarn, wood, plastic, etc.
& nbsp; & nbsp; & nbsp; & nbsp; 3. What are soft magnetic materials? What are their characteristics and uses?
& nbsp; & nbsp; & nbsp; & nbsp; Answer: Soft magnetic materials refer to ferromagnetic materials with low remanence and coercivity, such as silicon steel sheets, pure iron, etc. It is characterized by easy magnetization, easy demagnetization and narrow hysteresis loop. Soft magnetic materials are often used to make cores for electrical appliances such as motors, transformers and electromagnets.
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& nbsp; & nbsp; & nbsp; hard magnetic materials are often used to make permanent magnets, loudspeaker magnets and memory elements in electronic circuits.
& nbsp; & nbsp; & nbsp; & nbsp; (4) what is eddy current and what are its advantages and disadvantages in production?
& nbsp; & nbsp; & nbsp; & nbsp; Answer: The inner conductor (including ferromagnetic material) in alternating magnetic field will induce closed circular current on the cross section perpendicular to the direction of magnetic force line, which is called eddy current.
& nbsp; & nbsp; & nbsp; & benefit: induction furnace can be made to smelt metal by eddy current principle; magnetoelectrics and induction electrical instruments can be made by eddy current; dampers in watt-hour meters are also made by eddy current principle.
& nbsp; & nbsp; & nbsp; & nbsp; disadvantage: in electrical machinery, transformer and other equipment, the existence of eddy current will produce additional losses, while the magnetic field weakening will reduce the efficiency of electrical equipment, so that the capacity of equipment can not be fully utilized.