Draw 3 equipotential surfaces corresponding to a field that uniformly increases in magnitude but remains constant along positive Z-direction. How are these surfaces different from that of a constant electric field along Z-direction ?

Explanation

The three equipotenital surfaces are in XY plane.
As magnitude of field increases along positive Z direction, distance between successive equipotential surfaces (for given dV) decreases as shown in Fig. If electric filed were constant , distance between successive equipotential surfaces would stay constant.