# Fringing of electric field

I have read that in a capacitor with charged parallel plates the electric field lines are parallel in the middle, but they tend to bend outwards (causing a "fringe") towards the ends of the parallel plates. Can someone explain why this really happens? Does it happen due to the lack of symmetry, which is usually present in an infinitely long charged plate? It is to some extent obvious that the electric field isn't uniform at the ends, but why should they bend outwards only, can't they bend inwards?

• Think about what the equipotential surfaces should look like. Feb 22, 2020 at 6:22
• Can you provide a more foolproof explanation?I dont seem to get you. Feb 22, 2020 at 7:41
• Electric fields are governed by a partial differential equation with boundary conditions. Solving it is really nasty, so we "engineers" make crude approximations that serve their purposes. Ignoring edge effect is one such approximation. That is OK when the plate separation to perimeter ratio is small. Sep 3, 2023 at 23:09

The potential difference between the plates is $$-\displaystyle \int^{\large +}_{\large -} \vec E \cdot d\vec s$$.