Question

Equipotential surface associated with an electric field which is increasing in magnitude along the y-direction, are

• A. parallel to $XY$ plane
• B. parallel to $XZ$ plane
• C. parallel to $YZ$ plane
• D. coaxial cylinders of increasing radii around the the $x$-axis

Answer 1

The correct option is B parallel to $XZ$ plane

Electric field lines are always perpendicular to equipotential surfaces. Since electric field is increasing along $Y-$direction, it means the equipotential surface must be planes perpendicular to $Y-$axis, or parallel to $XZ$ plane.