In a uniform electric field, what is the shape of the equipotential surfaces?
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → Planar
An equipotential surface is normal to the electric field at every point. In a uniform field the field lines are parallel straight lines, all in the same direction.
Option (1) Planar — Correct. A surface that meets parallel straight field lines at right angles everywhere is a plane normal to the field. For example, a uniform field along the x-axis has equipotential planes parallel to the y-z plane.
Option (2) Non-planar — Incorrect. A curved equipotential surface goes with field lines that change direction from point to point. The spheres around a point charge are an example. A uniform field has the same direction everywhere.
Option (3) Ellipsoidal — Incorrect. An ellipsoid is a closed curved surface. Its normal points in different directions at different points. So it cannot be perpendicular to field lines that all point one way.
Option (4) Helical — Incorrect. A helical surface twists about an axis, so its normal keeps turning. It cannot stay perpendicular to parallel field lines.
NCERT (2026-27):
Equipotential Surfaces – “For a uniform electric field E, say, along the x-axis, the equipotential surfaces are planes normal to the x-axis, i.e., planes parallel to the y-z plane ….”