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Before answering the question of what electrostatic induction is, it is necessary to determine what exactly is understood by the term “conductor”. Although whole school topics are devoted to this at school physics lessons, a person who does not directly encounter repair and maintenance of electrical equipment often loses unused knowledge after some time. This is quite natural, therefore we recall the main points, without understanding which it is impossible to explain what electrostatic induction is.
Movement of charged particles in conductive materials
Imagine that a dry wooden block is included in an open circuit consisting of an ammeter, a resistor, and an electromotive force (EMF) source. The meter needle will remain at zero. But if you replace the tree with metal, then the ammeter will show the steady-state value of the current flowing through the chain. Therefore, depending on the resistance to the passage of current, all substances can be conditionally divided into three large groups - conductors, dielectrics and semiconductors. The most famous representatives of the first group are solid metals.
Conductor and field strength lines
If a metallic uncharged sample is placed in an electric field, then an ordered and directed motion of free carriers of electric charge, more commonly known as current, will appear in it. The vector of the lines of the field strength and the directivity of the current are opposite. In metals, conductivity is due to the movement of electrons. Since the sample is not part of a closed circuit, a redistribution of free charge carriers will occur in it under the influence of the field: on the one hand, electrons will collect, forming a negative potential, and on the other, their disadvantage will be formed, i.e. a positive sign. This phenomenon is caused by the action of an external electric field and is called “induction”. It can also be said that electrostatic induction is a phenomenon of redistribution of charge carriers caused by an electric field. It should be noted that the magnetic field also affects the conductor . So, the magnetic flux, penetrating the conductive material, creates an induced current in it. Also, as a result of magnetization, the induction of the material from the side of the external field and the arising internal field are summed. The term "complete induction" just designate this amount.
Field Interaction
Around each concentration of charges (+ and -), an intrinsic field arises from the edges of the conducting material. It enters into interaction with the external, and is directed towards it. Redistribution causes a decrease in the field of charges, this happens until its tension in the conductor itself becomes zero. In addition, the concentration of charges distorts the lines of the external field in such a way that they become perpendicular to the material. Earlier, we specifically indicated that we are talking about an uncharged conductor. Electrostatic induction is characterized by the fact that although the distribution of charges occurs in the conductor that has entered the electric field , it remains uncharged.
Features
Since the charges tend to occupy the most extreme positions, they are located on the surface of the sample. Even if there is an internal empty space, the field inside eventually tends to zero. This allows you to organize effective protection of sensitive devices from external electromagnetic fields. A “protected” object is placed inside a conductor sphere (a metal grid is also suitable): induced charges accumulate on its surface, form its own field, which balances the influence of the external inside the sphere.