Short Answer:
When a conductor is placed in an electric field, the free electrons inside it start moving due to the applied field. This movement continues until the charges rearrange themselves in such a way that the internal electric field becomes zero.
As a result, positive charges appear on one side and negative charges on the opposite side of the conductor. This process is called electrostatic induction, and it stops when equilibrium is reached.
Detailed Explanation:
Conductor in electric field
Initial effect of electric field:
When a conductor is placed in an external electric field, the free electrons inside the conductor immediately respond to the field. Since conductors have many free electrons, these electrons start moving in the direction opposite to the electric field. This movement of charges happens very quickly.
Due to this motion, electrons gather on one side of the conductor, making that side negatively charged. The opposite side loses electrons and becomes positively charged. This separation of charges inside the conductor is called charge redistribution.
Formation of induced charges:
As electrons accumulate on one side and leave the other side, induced charges are formed. These charges are not added from outside but are rearranged within the conductor itself. This effect is known as electrostatic induction.
The induced charges create their own electric field inside the conductor. This internal field is in the opposite direction of the applied external field.
Final condition
Zero electric field inside:
The movement of electrons continues until the internal electric field cancels the external electric field. At this stage, the net electric field inside the conductor becomes zero. This condition is called electrostatic equilibrium.
Once equilibrium is reached, no further movement of charges occurs. The electrons stop moving because there is no net force acting on them inside the conductor.
Charge distribution on surface:
At equilibrium, all excess charges remain on the surface of the conductor. There is no charge inside the conductor. The distribution of charge on the surface depends on the shape of the conductor. Sharp edges tend to have more charge concentration.
Potential inside conductor:
The electric potential inside the conductor becomes constant throughout. This means there is no potential difference within the conductor. Since electric field is related to potential difference, zero field means constant potential.
Behavior of electric field lines:
Electric field lines do not exist inside the conductor at equilibrium. Outside the conductor, the field lines are perpendicular to the surface. This shows that the conductor adjusts itself to block the internal field.
Practical importance:
This behavior is very important in many applications. It is used in shielding sensitive electronic equipment from external electric fields. It also plays a role in the design of conductors, capacitors, and transmission systems.
Relation with electrostatics:
This concept is a key part of electrostatics. It explains how conductors behave under electric influence and helps in understanding many electrical phenomena.
Conclusion:
When a conductor is placed in an electric field, free electrons move and redistribute until the internal electric field becomes zero. Charges settle on the surface, and the conductor reaches electrostatic equilibrium. This behavior is important in many electrical applications.