What do you understand by electrostatic shielding? Explain its significance.
Electrostatic Shielding: The method of protecting a region from the effect of external electric field is called electrostatic shielding.
When a conductor having a cavity of any shape is placed in an external electric field, the charges of conductor re-distribute and resides on the outer surface of the conductor as shown in figure 33. The electric field inside the conductor including cavity is zero. Thus, the cavity in the conductor will not experience any force due to the charges on the outer surface of the conductor. This is called electrostatic shielding. The concept of electrostatic shielding is used to protect sensitive instruments from the effect of strong electrostatic fields by enclosing these instruments in a metallic cage.
It is for this reason that it is safer to sit in a car or a bus during lightning and thunder rather than to stand under a tree or on the open ground.