Effect of a conductor situated within an electric field

Example II Effect of a Conductor Situated within an Electric Field 

We will now consider a second example which illustrates the electrostatic induction phenomenon. First of all, let us suppose that a conductive body of arbitrary shape is situated within the region of influence of an electric field Eq as shown in Fig. 1.9. Under the action of the field, the positive and negative charges residing inside the conductor move in opposite directions. As consequence of this movement, electric charges accumulate on both sides of the conductor. In so doing, they create a secondary electric field, which is directed in opposite direction to the primary field inside the conductor. The induced surface charges distribute themselves in such a way that the total electric field inside the conductor disappears, that is  

Returning again to the electrostatic induction phenomenon (Fig. 1.9), it should be obvious that the secondary electric field contributed by the surface charge can be defined from the equation  

for instance, a single point charge e is situated outside the conductor, electric field at any point inside the conductor is  

It results from this fact that the electric field caused by a given system of charges does not depend on the properties of the medium. If the field changes, this means that new charges develop. 

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