‘X’ is the phenomenon of making a region free from any electric field. Identify X.
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → Electrostatic shielding
Option (1) Electrostatic induction — Incorrect. Induction is the separation of charges on a conductor when a charged body is brought near it. It is about the redistribution of charge, and it does not keep a region free of field.
Option (2) Electrostatic shielding — Correct. A cavity in a conductor stays shielded from outside electric influence. The field inside the cavity is always zero, whatever the charges and fields outside. This is used to protect sensitive instruments.
Option (3) Gauss’s theorem — Incorrect. Gauss’s law relates the electric flux through a closed surface to the charge it encloses, \( q/\varepsilon_0 \). It is a law about flux and gives no way of removing the field from a region.
Option (4) Corona discharge — Incorrect. Corona discharge is the leakage of charge into the air from the sharp points of a highly charged conductor, where the field is very strong.
NCERT (2026-27):
Electrostatics of Conductors – “… Whatever be the charge and field configuration outside, any cavity in a conductor remains shielded from outside electric influence: the field inside the cavity is always zero. This is known as electrostatic shielding.”