An equipotential surface is a surface where every point on the surface has the same electric potential. In other words, it is a surface over which the potential at every point is equal. The work required to move a charge from one point to another on an equipotential surface is zero. Equipotential surfaces can be used to visualize electric fields and are perpendicular to the electric field lines. Some key properties of equipotential surfaces are:

• All points on an equipotential surface have the same electric potential.
• The electric force neither helps nor hinders motion of a charge on an equipotential surface.
• The direction of the electric field is perpendicular to the equipotential surface.
• For a point charge, the equipotential surfaces are concentric spherical shells.
• For a uniform electric field, the equipotential surfaces are planes normal to the x-axis.
• Inside a hollow-charged spherical conductor, the potential is constant, and this can be treated as an equipotential volume.

Equipotential surfaces are used in various fields, including electrostatics, electrodynamics, and electrical engineering.