In: Physics
Explain why equipotential surfaces are always perpendicular to the electric field lines. Do equipotential surfaces ever intersect?
For a point charge electric field lines are radially outward or inward depending upon the nature of the charge.
Equipotential surface passing through a point is normal to electric field at that point is simply follow from if field was not normal to equipotential surface then work is needed to be done in moving a charge from one point to another but this isn't true.
On a equipotential surface no work is needed to be done in moving a charge from one point to another that means force must be normal (at 90°) to the surface.
If force (E) was not normal to equipotential surface than within the surface potential would not have be equal at every point rendering surface not equipotential at all.
So if a surface has potential same at every point in it (equipotential surface) that means electric field must be normal to this surface that's why no work is needed in moving a charge from one point to another on the surface.
magnitude of E = -∆V/∆l