Question

Equipotential surface are perpendicular to field lines .Why ?

Answer 1

In this case the "altitude" is electric potential or voltage. Equipotential lines are alwaysperpendicular to the electric field. In three dimensions, the lines form equipotential surfaces. Movement along an equipotential surface requires no work because such movement is alwaysperpendicular to the electric field.

Answer 2

Hi friend ,

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No work is done in moving  a charge from one point on equipotential surface to the other . Therefore, component of electric field  intensity along the equipotential surface is zero . it means the electric  field intensity is perpendicular to equipotential surface . hence, the surface is perpendicular to the field lines.
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