Question

Why can you shield an object from an external electric field using a conductor?

Answer 1

A conductor shields an object from an external electric field by redistributing its charges to create an induced electric field that cancels out the external field both inside and around the conductor. This process results in no net electric field within the conductor, effectively screening the region outside from the external electric field.

Answer 2

A conductor can shield an object from an external electric field by becoming an equipotential surface. Connecting the conductor to the earth through grounding keeps the conductor at zero volts relative to the earth, preventing charges from flowing and shielding the object.

Step-by-step explanation:

One of the rules for static electric fields and conductors is that the electric field must be perpendicular to the surface of any conductor. This implies that a conductor is an equipotential surface in static situations. There can be no voltage difference across the surface of a conductor, or charges will flow. One of the uses of this fact is that a conductor can be fixed at zero volts by connecting it to the earth with a good conductor-a process called grounding.

Grounding can be a useful safety tool. For example, grounding the metal case of an electrical appliance ensures that it is at zero volts relative to the earth.